To add to this point, Avatar is actually more than an old story: it's a boilerplate movie plot. Anyone who is educated about script writing knew exactly what it was by minute 20 because it followed the formula to a T.
The reason the formula exists is that it's versatile. Anyone can plant themselves inside and understand it from their worldview. That's why it's so similar to other movies, and that's why people can see the Vietnam war and Chinese real estate developers in it.