The speck is in your own eye, I think.
The Narn are certainly sounding the war drums at the beginning of the show, but that isn’t enough to make them “war–like”. The Centauri and the Minbari are both better at war than the Narn. Two of the Narn characters are the most eloquent and intelligent of any characters on the show. The humans and Minbari fought a war just ten years before the show starts, and you didn’t put either of them down as “war–like”. The Minbari nearly committed true genocide and wiped out the human race completely, but you called them mystics instead.
The Minbari certainly seem like mystics, at least until you meet a few members of the Warrior caste; the diplomats we see at first are only from the Religious caste. And when considered in detail their philosophy is not really very similar to any “Eastern” philosophies you might be thinking of.
But the decadence of the Centauri Republic is intended to remind you of the Roman Empire. There are differences, but that aspect of the Centauri was intended to feel especially familiar. Humans can grow to understand the other races, but they could easily _be_ the Centauri.
The question of religions and philosophy is an interesting one.
Depending on how much of the show you watched, you may have found out that they believe in reincarnation (in fact that think that was a big plot–point of the second or third episode). This is certainly a point of similarity with one “Eastern” religion that I can think of. However, the Minbari have _scientific proof_. The Warrior caste Minbari believe in reincarnation even though they are not religious, because it’s been proven. There are people in the universe who call it a “pretty fantasy” so the question is left open for the viewer, at least until later. However, in other respects their philosophy is not much like that of any human religion which incorporates a belief in reincarnation. Hinduism has reincarnation and castes, but it also has a pantheon of gods. The Minbari have reincarnation and castes too, but no gods at all. Their most revered religious figure is “a Minbari not born of Minbari”; in other words an ordinary Minbari of unusual heritage but not a supernatural being in any way.
Meanwhile, the Centauri believe that they can often see the circumstances of their own death. “Comes in a dream, yes?”. Again, this is something even non–religious Centauri believe. Londo tells Sinclair about his dream, that he has always known that he would be strangled to death by a Centauri (“We are squeezing the life out of each other.”). And he says that as soon as he saw G’Kar for the first time, he recognized him as the Narn in the vision. We the viewers are actually shown the vision, and in season 4 the show follows through and we see how Londo’s death plays out. The Centauri also have Seers who can see the future of other people, and those visions always happen exactly as we are shown them. Meanwhile, the Centauri religion is in many ways the direct antithesis of Christianity, a major human religion that has a strong element of prophecy, and one that became common in the Roman Empire no less. Their religion is much more similar that of the earlier Roman Republic with a whole pantheon of deities, including at least one ascended emperor.
It’s not as important to the plot of the show as the others we see, but in the fifth season we learn that every 200 years on the Brachiri homeworld the dead come back to life for a night to talk to the living and give them advice. And this works not just for the Brachiri; a human on the Brachiri homeworld or on any property owned by the Brachiri during that night will be visited by someone from their own past. One of the visitors, a human who died years before the show begins, relays a message from a character that died in season 3 to one that is still alive, but who wasn’t within the Brachiri zone!
I’m not really sure how to classify the Narn religious beliefs, but at least one of their religious texts contains accurate historical information that turns out to be useful to the main characters.
So in the Babylon 5 universe, many species have religious beliefs that are actually literally true. Those religions share some broad strokes with religions that exist here on Earth today, but not much more than that; the details are always quite different. There’s more depth there than you thought.