After the rapid plot advancement/mystery solving of And the Sky Full of Stars (which, of course, only creates more mystery), B5 goes into a run of episodes that mostly aren't as bad as, say, Soul Hunter or Infection, but are honestly just... inessential. I skimmed through Deathwalker three times looking for important moments to pull out, but didn't feel like there was anything that wasn't covered in other episodes. Believers was a big deal when it aired, but it's a lot clumsier than B5's usual nuanced approach to religion (it reminds me, unpleasantly, of everything I didn't like about the way Bajoran religion was handled on DS9). I find it excruciating to watch, and know a couple of fellow fans who refuse to acknowledge it exists. And Survivors is backstory about Garibaldi, but really the only important thing about it is that he falls off the wagon. Ultimately, you don't need to watch them and unlike By Any Means Necessary, which is also inessential but I've added to my must-watch-in-full list for quality reasons, I don't recommend that you do unless you're invested and just want more early B5 content.
(Believers is about some alien parents who refuse medical treatment for their son because of their religious beliefs. They think that if someone is cut open, their soul escapes. Franklin goes ahead and operates on the kid to save his life over their objections. They kill their child, believing they're putting a soulless shell out of its misery. It was an Extremely Big Deal at the time that the kid died.)
There are a few important plot points or things that get called back to here, but I can summarize them quickly:
Kosh hires Talia to help him with some negotiations, but they aren't what they seem. It becomes apparent that he's recording her reactions. When she asks why, he says, "Reflection. Surprise. Terror. For the future."
Vorlons don't seem to like telepaths.
The League of Non-Aligned Worlds, which is an alliance of a lot of alien species without the sort of power possessed by the Minbari, Centauri, or Narns, has representatives on B5. They allied with Earth during war with a now-extinct species called the Dilgar.
Kosh quote: "Understanding is a three-edged sword." (JMS annotation: "Your side, their side, and the truth.")
There has been some sort of outside interference with Minbari religion in the past.
Kosh quote: "The avalanche has already begun. It is too late for the pebbles to vote."
There's an attempt to assassinate President Santiago.
Garibaldi's an alcoholic who falls off the wagon in this episode.
The B-story, with Londo and G'Kar wrangling, provides some good character moments for both.
The A-plot is one of Season 1's better written, directed, and acted. It's an old-fashioned union story, and a good glimpse of Babylon 5 functioning as both a trade hub and a military base--and the potential conflicts of interest that entails. It was written by JMS's wife, Kathryn Drennan, after some pushback from JMS, who didn't want to give the appearance of (or engage in) nepotism. Fortunately for everyone, she won that argument... and delivered. While it doesn't exactly provide any *details* that are important to the arc, it sets the stage for B5's often-contentious relationship with EarthGov.
The most obvious ancestor to The Expanse is Battlestar Galactica, but BSG arguably owes more to B5 than the various Star Treks, even given Ron Moore's work on DS9. This episode (and the upcoming two-parter Voice in the Wilderness in its exploration of Mars' rebellious relationship with Earth), with its working-class space residents versus privileged Earthers, show some scifi DNA that skipped a generation and went straight from B5 to The Expanse.
The Rush Act, incidentally, is named for Rush Limbaugh, a characteristically sly dig that probably dates it (when was the last time he was relevant?) but is fun nonetheless.
TKO is one of the low points in the first season--an attempt to do a martial arts movie complete with awkward dialogue, a hackneyed plot, and some Asian stereotypes that haven't aged well. It can't quite be said to be one of those martial arts movies in which a white guy learns the martial arts of an Asian culture and then is magically better at it than all of the members of the culture he learned it from, since the protagonist in this case is Black, but sub in "human" for "white" and "alien" for "Asian" and it follows the formula to a T. There's nothing significant to the arc in it, and no reason to subject yourself to it.
The B-story, however, is pretty well done and made it one of the most memorable episodes of S1 for me.
The plot is pretty simple: Ivanova's childhood rabbi (played by Broadway's most tenured Fiddler on the Roof star, Theodore Bikel) comes to Babylon 5 and tells her she should sit shiva for her father. She resists, because she's still angry at him.
***
So, look, this might not seem like that big of a deal if you're not Jewish, but I am Jewish, and I'm going to talk about it.
There are very few scifi shows showing future worlds in which Jews exist. Oh, we get a lot of analogues for Jews--depending on who you ask, and which episode it is, Star Trek has the Bajorans, the Ferengi, and the Vulcans; Mass Effect has the Quarians and, more problematically, the Volus--but while Federation culture in Star Trek appears to be predominantly white Christian culture (they may no longer exactly practice Christianity, but they celebrate Christmas, the morality is Christian, and characters quote the Bible), and there are representatives from many different Earth cultures (O'Brien is emphatically Irish, Chekov is Russian, Picard is French), there appear to be no Jews, at least in the shows and movies. Similarly, in The Expanse, various recognizable denominations of Christianity (the Mormons, the Methodists, the Catholics) survive into the future, but even at interfaith clergy gatherings, there is no sign that Judaism is still practiced at the time the series takes place.
For a member of a people that's survived several thousand years of people trying to wipe us out, the idea that scifi writers believe that a few hundred years from now, we'll be gone is pretty depressing.
Similarly, while there's no shortage of Jewish characters in non-SF TV, there's very little Jewish ritual shown (unless, obviously, the show is actually about Jews, e.g. The Marvelous Mrs. Maisel), and when it is shown, it's usually in the context of a Very Special Episode (see, for example, The Good Wife's "Unorthodox" or Law & Order's "Chosen") in which Orthodox Judaism (and by extension, Judaism in general) is treated as an exotic, anachronistic culture more like the Amish than the majority of American Jews. When Jewish practice is shown, it's generally either the parts that most resemble Christianity (e.g. a rabbi giving a sermon in The West Wing; Hanukkah celebrations because Hanukkah's just Jewish Christmas, right?; the actual burial part of a funeral) or the party after the actual ritual, usually a bar mitzvah or wedding. Maybe the main character will visit a Jewish family that's sitting shiva, but there won't be any ritual going on at the time other than the mirrors being covered and people wearing black.
What you don't see is what day-to-day Jewish ritual practice actually looks like: lighting Shabbat candles, saying blessings, celebrating holidays that aren't Hanukkah or Passover, studying Torah, touching the mezuzah when leaving the house.
It was already a big deal that, at the end of The Parliament of Dreams, the show emphatically noted that Jews exist in its universe (and, perhaps, in all of our diversity! since that line of adherents of different religions is really long, and Sinclair calls out that the Jewish guy is specifically an Orthodox Jew). Dayenu! But we get more. The second-in-command of the station is Jewish.
And she has possibly the most realistic relationship with her Jewishness that I've seen on TV: a fraught one.
And--and!--like most modern non-Orthodox Jews, she's gotta figure out how to make Jewish ritual work for her (as my rabbi's fond of saying, the purpose of Jewish practice is to serve the needs of Jews, not the other way around) while making it accessible to the non-Jewish loved ones she wants to include.
Just as beautifully, Ivanova's either not the first Jew Sinclair has considered a close friend, or when he got to know her, he read up on Judaism, because he's a lot more familiar with Jewish ritual than your average non-Jewish human. Either way, between the Orthodox man in The Parliament of Dreamsand Ivanova and Sinclair's implied Jewish friends and the Jewish residents of the station who show up to support Ivanova in mourning and Ivanova's rabbi and a rabbi who collaborates with a priest in helping pass on important information later in the series, not only are Jews still clearly around 300 years from now, but they're not tokenized, and in fact, seem to be thriving.
Look, it's not perfect. The morality of B5 is very Christian (not least in its love of martyrdom--Delenn even says that willingness to self-sacrifice is a requirement for sentience), and the pressure on Ivanova to forgive feels pretty Christian to me, but that's a small quibble.
Babylon 5 is a series written by an agnostic that is fascinated by the same questions human religion is designed to explore (less interested in the how of things than the why) and that is comfortable leaving mysteries unsolved. A lot of scifi seems annoyed that it has to deal with religion at all, or uses it as a shorthand for the primitive irrationality that human beings retain, even in the future. For all its Christian morality, B5 seems to view religious practice itself much the way my Jewish community sees it: as less interested in answering questions about God than cultivating wonder and exploring what it means to be human).
As the rabbi says, nes gadol.
***
So, anyway, skip the A-story, enjoy the B-story.
It's perhaps most significant in that Ivanova, who up until this point has been pretty private and buttoned-up, finally is willing to recognize that her crew cares about her and be vulnerable around them.
Ivanova's mother's suffering, as a telepath who wouldn't join PsiCorps, was even more intense than we've heard about previously.
Ivanova joined Earthforce against the wishes of her father.
Sinclair is willing to walk right up to the line of forcing people under his command to take leave if he thinks their emotional health is at stake.
Ivanova and her rabbi have a nice discussion about whether an alien form of fish is kosher, which is the sort of question that Jews have enjoyed debating since the possibility of space travel became a thing (there was even a long-running thread on how to determine whether you can eat an alien, which, alas, I'm having trouble finding).
Grail's another one you can just skip. It's not terrible, especially for Season 1, but it's also not particularly good (and everything having to do with a character named Jinxo is... really not good), and the Arthurian/Tolkienesque ground will be covered, with more relevance to both the arc and B5's themes, in a later episode.
There's kind of a funny scene in which humans are suing gray aliens for abductions.
Honestly, the only important part of Grail that I noticed as important is the reminder of the Babylon Project's history.
"When I first came here, this was all swamp. Everyone said I was daft to build a castle on a swamp, but I built in all the same, just to show them. It sank into the swamp. So I built a second one. And that one sank into the swamp. So I built a third. That burned down, fell over, and then sank into the swamp. But the fourth one stayed up. And that’s what you’re going to get, Son, the strongest castle in all of England."
Ooops, sorry, wrong IP.
When humans first came there, it was all space. Everyone said they were daft to build a space station there (Lloyd's of London put the odds of success at 500 to 1!) but they built it all the same, just to show them. Its infrastructure collapsed due to sabotage. So they built a second one. And that one exploded during construction. So they build a third. That one exploded too. So they built a fourth. That one mysteriously disappeared 24 hours after it became operational. But the fifth one stayed in orbit. And that's what we got, dear reader, the strongest station in all the galaxy.