Another component for the storyline I've laid out: Jake would be portrayed as having largely given up on human beings as a species. He did, after all, decide to stop being one. He's sick of them, and returning to earth is like prying open a scab for him. Neytiri would be very confused by it all-- frightened, perhaps even a bit fascinated, but ultimately these are the same people who invaded her home 10 years ago, and she doesn't particularly like them. Their daughter, on the other hand, would actually have some fondness for the humans.
The fact that she is also technically half earthling by birth would probably play into the story as well, since she would be discovering a lost part of her heritage. Jake tried his best to shield her from his own human nature, but in a way that just made her more curious about that part of her. Having ancestry with the humans could be part of what compels her to save them.
She recognizes humans as being flawed, but she sees them as being confused and complacent rather than evil. Even though she was brought to Earth against her will, she still has a desire to save the humans from themselves, even though her parents just want to get off the planet and go home, which would lead to some conflicting interests later in the film.