In this movie, I think the most impressive point is Navi keep the balance of life and death. That idea is not only for Navi people themselves but also the life in the nature, like animals. In other words, they keep balance of ecology following their indigenous way. When Jake is about to be attacked by the wild animals, A Navi named Neytiri serves him. After she helps him, she warns him that they are unnecessary to die, being irritable. It means she does not want to kill them as possible as she can.
Thinking about our life, for getting more advanced life, we are trying to change every possible day by day. After this movie, I think it may destroy the balance of life and death.