There is a big reason why people latched onto the villain rather than the main protagonists, because it's the same archetypes we've seen before in those kinds of movies.
Did anyone really latch on to the villain? I mean, like any good villain, he stood out for all the archetypical villainous reasons. If anything, I still find Neytiri to be closer to the main character, even though we don't experience the story through her eyes. As well as the character I most enjoy from the film.
The problem is Cameron made the aliens too perfect to identify with them, and they are never portrayed as wrong or really nuanced as a group of people.
I'd disagree with this pretty strongly. I never thought of them as perfect at all. The tensions between Jake & Tsu'tey about his role within the Omaticaya Clan as an outsider specifically helped to give some depth to the Na'vi as a group of people especially in terms of their nuances on how they have differing views of the Humans and Avatars and the varying relationships that they've had with them since they arrived on Pandora.
'Tis a good point. I've seen the observation made before (maybe it was here, maybe it was tumblr) that for a movie that made so much money and was seen by so many people, our pop culture is oddly lacking in memes or other references to the thing. I've heard a grand total of one, and that was in person rather than on the Internet.
I have speculation here, but I don't have a lot of evidence other than the lack of evidence that you mention. I think that Avatar really broke out as a film
experience more than anything else, which was in some ways helped by the fact that its story was incredibly simple and not like a lot of scifi things that have a bigger barrier of entry for their settings and plots. Avatar was accessible, and the sort of thing that, when it was released HUGE word of mouth got around as it being something that you NEED to see in the theater, moreso than I think probably any other film's ever had.
For good or bad, the setting and the experience of BEING on Pandora that the theater experience delivered wasn't like anything that came before it, and while 3D is much more of a staple in films these days, VERY few other films have really crept into that space of inhabiting the space behind the screen as well as Avatar did (although I'd personally put
Dawn of the Planet of the Apes in that category as a close second – again, the work with Performance capture and transmutive performance here is a HUGE factor).
As such, it's not like Star Wars where you're quoting scenes or talking about ships and things, and it's not like other films where you're pouring over the nuances of the story, but it definitely made an impact in a VERY different way, but one that doesn't really serve itself to being shared or discussed in the same way we usually discuss films.
Again, I think that a LOT of this comes down to the mechanics of how the film was intentionally shot and assembled to be that kind of experience. The Performance Capture technology combined with the virtual cameras letting him pick shots in ways that literally aren't possible with traditional filmmaking AT ALL is something that you can't really properly sum up in discussion (a lot like trying to describe using really good VR after the fact).
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