I personally thought the movie was not about native Americans, but rather about what could become of humanity in the distant future, given we survive and solve our energy problems fast enough to develop means of intergalactic space travel.
A species so dumb, greedy and evil that the few decent members, given the opportunity, would willingly choose to rather become a member of a different sentient species on a distant planet and start to kill their own (former) brethren. Come to think of it - that’s already the case today, I believe. At least for some people I know.
I didn’t expect a mindblowing story script, not with such a focus on visuals being the base of the whole movie project from the very beginning. But the story was moving, the action was tense, the music was fitting and the “rallying of the clans” with the protagonist quietly narrating from off the screen even got a tear into my eye, so it was good enough for me to be drawn into it. I might be easily moved, but well - all the better for me, eh?
For a movie that supposedly was not scientific enough to be science fiction, there was pretty much science in it.
Advanced but recognizeable weapon systems (loved the 'copters), cryogenic stasis chambers, space travel ships the size of the ISS and with rotating sections to simulate gravitational force, aerodynamic dropships designed to penetrate atmosphere and transport personnel onto a planet’s surface, an earthlike planet being one of the moons of a gas giant in a distant solar system, having less gravitational force than Earth and thus being home to much larger and taller species than our homeworld, alien species capable of engaging in temporal symbiosis with many different kinds of animals and plants, genetically engineered host bodies made from alien and human dna for the purpose of using them as “avatars” by projecting the conscious of a human being into them by technological means, advanced display technology (detachable, transparent holoscreen displays) and so on and so on…
No science fiction? Come on… give credit where credit is due.