As far as the BSG genocide debate goes, the short version of my opinion is Helo did the right thing ethically but not the right thing practically, and I would definitely have done the latter (as savagely immoral as I concede to consider it).
However, whatever one thinks of Helo and the rest of the BSG cast, it's clear they're not
written to be the bad guys. The series toys a lot with the moral complexities of the leads, but when it lays the cards on the table it considers even the most screwed up human principals - Starbuck and Tigh - as basically good people.
The only principal human character on the show who could be considered a villain is Baltar, but there are good elements and arguably a redemption of sorts - though whether one feels that's character assassination in reverse is probably a matter of taste, I happened to mostly like it.
Point is, this is a far cry from the corporation boss in District 9, who is wholly and utterly unethical, and how I suspect Stephen Lang's character in Avatar is going to be played. These are uncomplicatedly evil men who sleep well and sort of what one would mean when referring to 'evil humans.' BSG did do a story about characters like that - it was called "Pegasus." If BSG
had been a story about evil people, it would have been Admiral Cain's story, not Adama's.
I can't speak much more on Avatar, since I haven't seen it, and Kegg has been following it much more closely than I have.
Mostly just by catching all the trailers as they came out, I'll admit this film wasn't even on my radar until I saw the first trailer.
Hyperspace05 seems by far the most well informed to regularly post about it.
Your argument is nullified by what I wrote above. There is no clear humans=bad, Navi=good division in the film. Just wait and see.
So there are evil Na'vi, then? That might convince me.
Ah, but the original question was:
In that case, where has a proper example been provided where none of the human characters have been depicted as good?
Whether or not there are evil Na'vi is beside the point, no? If there are good humans in Avatar, and there are, it doesn't qualify for this.