I wish a Sci-Fi setting would have varying human nations expand into such an alien setting and fuck shit up as humanity alternates between cooperating with each other to shit on alien powers if they're too tough for one nation to crush and competing with each other over the rewards of said wars when there's lulling in between shitting on them like we would.
I don't think it works at scratching the core space opera itch, which is the Little Guy doing Outsize Things. Humans have the be young, scrappy outsiders who punch above their weight -- either because they're uniquely creative (a typical trope, one variant of which is that they're not so much creative as newcomers who don't know the "box" well enough to think inside it) or uniquely good at war or uniquely determined to never give up. In the U.S., at least, that seems to be part of recreating the glorious youth of our nation in space -- at the end of the day, it's the tired old empires of Europe who have to beg us to save them from dark forces, etc.
You could do it your way, but I think you'd just degenerate into having one of the human factions be the Little Guy, and go from there. Incidentally, it is typical to have a Little Guy within the Little Guys: the academy goat who turns out to be the one captain who can save the day; the man summoned from the past; the sole survivor of a fatal accident. Typically he (and it is typically
he) will be opposed by Big Guys within the Little Guys -- a blind and priggish admiral, a feckless and peace-desperate politico, a war-crazy and xenophobic general, perhaps
all of these guys.
Incidentally, all of these are pretty important because an outsider can receive expository dialogue and narrative more easily and a Little Guy can be the focus of the action in the way that a Big Guy (who necessarily is defined by the vast bureaucratic machinery in which he is situated) cannot be.
Straczynski's inspiration for B5 was Tolkien's Legendarium first and foremost. He admitted that he essentially took each race in Tolkien's work and slightly changed them to be aliens to fit into his world, the most apparent being theElvish Minbari.
He wedded Tolkien with the many-alien-factions brand of space opera. Too much of Babylon 5 is too obviously traceable to existing space opera books -- the entire Stephen ?? doctor guy is straight out of the sub-sub-genre that includes Sector General, for example. Obviously the Minbari / rangers thing and the Ancient Evil is pure Tolkiena, but I think crediting JMS with building it from that foundation is giving him too much credit.
This argument is also showing how transparent the divide between Science Fiction and Fantasy is
I'm not so sure. I spent a big chunk of my childhood reading fantasy (basically the only thing I read from 10 to 18, and back then I would read something like 100 books a year) and then, like I said, a couple years reading space opera (probably no more than 100 books total, though). The two feel very different to me. For one thing, fantasy tends to emphasize
items in a way that space opera doesn't: the problem, and its resolution, often turns on a particular
thing or
things. Not always, but with some regularity. That is rarely the case with space opera. There are other distinctions, but that one stands out immediately to me. I think planetary romance (
e.g., John Carter of Mars) is probably classifiable as fantasy though.
It's kind of odd to chart -- it's definitely not a two-dimensional spectrum, more like some kind of polygon.
For example, down one vector you can go from Pure Fantasy to Crossing Over Fantasy (
e.g., Narnia) to Fantasy-In-Our-World (
e.g., Harry Potter) to Cyberpunk to Pure Sci-Fi. But on that route, you never come anywhere near Space Opera. That route is more like Pure Fantasy -> Epic Fantasy (
e.g., LOTR, Shannara) -> Sword & Sorcery (
e.g., Fafhrd and the Gray Mouser, Conan) -> Planetary Romance (
e.g., John Carter of Mars, Planet of Adventure) -> Fantasy Space Opera (
e.g., Star Wars or WH40k) -> Soft Space Opera (
e.g., The Dark Wing, Babylon 5) -> Hard Space Opera (e.g., Revelation Space, the Culture series) -> Core Sci-Fi.
At the margins, things definitely get blurry, but I still think you can define categories with at least a
little bit of confidence.