Bear in mind, this thread is the result of some tired guy, thinking he has made a good point, and through my sleep deprived state at this moment in time, i am trying to write these thoughts down, if it does not make sense just tell me
Could the human invasion been some religious test by Eywa?
Like "Job" in the bible, no matter what your beliefs are, this particular man was tested by god, had his family killed, and had his crops and source of money destroyed, but he retained his faith, and prayed to god every day to keep him going. This showed to god, the extent of some people's beliefs, and how nothing could overcome them.
This is similar in the case with avatar, the human invasion brought suffering, misery and pain to the na'vi people, but through this they retained thier belief in Eywa, prayed to their deity in times of great sadness, and never lost their sense of community, and in the end they had their faith rewarded.