The Americans, who go to Pandora from their dying Earth, are in search of a very expensive mineral that happens to grow underneath a sacred tree that the Navi live in. Their plan is to negotiate relocation for the natives or to force them out, essentially threatening genocide. This isn't the first time Americans have been portrayed as land-stealing or resource-pilfering tyrants, but it is an interesting depiction of the Earth-pilaging actions of humans in general, from conflict-diamond mining to oil digging. Whereas most people might leave the theater agreeing that America is a highly invasive and capitalist nation, what they should leave with is the overarching idea that it has become human nature to take from the Earth without weighing the consequences.
The Navi believe that everything in nature is connected. They can emotionally and physically connect with anything, from a horse-like creature to even a fluorescent willow-like tree using what appear to be neurological chords that extend from within the ends of their long braids. They use these chords to become bonded with creatures, to gain their trust and share their strength. They believe in giving back to the Earth and showing appreciation for its gifts, apologizing to a creature when they kill it for food, and thanking their planet for giving life to a friend as they bury them. They only mourn unnecessary deaths for they understand the Circle of Life and never question the natural course of things.
Worthington's character was just as compelling as the Navi themselves. He was a Marine forced into retirement after a spinal-cord injury that left him handicap. He agreed to go on this expedition with his twin scientist brother, but his brother was killed before they shipped out. The mining company had an avatar created from the genetic material of his twin, so they figured not only could Jake replace him, but also act as a mercenary and infiltrate the Navi to gain their trust and map-out their headquarters for future invasion.
"The Navi say that every person is born twice—the second time is when you earn your place among the people." I believe that Jake's rebirth occurred in four stages. The first was the first time he connected with his avatar. Having been handicap for so long, I knew he would leap up onto his new feet the moment he regained consciousness, eager to run again and feel the soil between his toes. Considering how many hours the other avatar users needed to log in before being able to even stand, it was as though Jake were a natural. The second stage was when he bonded with his Banshee and participated in the Navi ceremony that was a cross between a Bar Mitzvah and knighthood. It was as though as a crippled person he didn't really feel like a Marine anymore, even though he was hell-bent on proving that he was. Being inducted into the Navi tribe was like joining a new brotherhood and regaining the respect he once had as a soldier. The third stage [MAJOR SPOILER] was when he did what only five other Navi were capable of accomplishing: bonded with the fiercest creature in the sky, the Leonopteryx. When the Navi, who had previously shunned him for his betrayal, realized the honor that he possessed, they could no longer deny his place in their tribe. He was not only a warrior, but a leader. The final stage was when he chose to become a Navi for real on his birthday and transfer his soul from his human body to his avatar, completing his transformation [END OF MAJOR SPOILER].
However, Jake made an interesting observation when he first met his avatar. He said it looked like his twin brother, which prompted his scientist pal Norm (Joel Moore) to point out that that meant it looked like him. I felt like in getting to bond with his brother's avatar, he was also getting to bond with his brother. So in that sense it felt more like Jake was being completed, discovering his other half, rather than being reborn. In the end, when the final battle occurs, he is riding the Leonopteryx in his avatar-form, while toting a machine gun and communicating with his friends through headphones. He combined his Navi warrior training with his Marine training, creating an ultimate soldier.
While the film does address spirituality, it labels it simply as faith and not a specific religion. However, there are remnants of Hinduism, Greek mythology, and Christianity within it. When I initially searched for Avatar in Wikipedia, it gave me the encyclopedia definition, which is a Hindu representation of a holy being that comes from heaven to earth, and is translated into English as an "incarnation." In Greek, Pandora means "giver of all." She was made out of Earth as a punishment to mankind for stealing fire. She's mainly known for releasing all the evils of the world, but she managed to safely lock away Hope and that is exactly what this planet of Pandora possesses. The representation of Christianity is in the Navi's Tree of Life, which not only gives knowledge but provides guidance. [MAJOR SPOILER] When Dr. Grace is wounded, they attempt to transfer her soul into her avatar using the fluorescent roots of the tree. She is adorned in leaves, much like Eve was. You could say as a scientist, she represented the Eve that asked too many questions and sought too much knowledge. Even as she was being brought to this sacred place that no humans were allowed to visit, she told Jake that this would be a perfect opportunity to get samples. You could even say that the reason it didn't work for her and it did for Jake was because he simply did as he was told and did not question the will of their world. He accepted this Garden of Eden and respected the balance of power that it required. [END OF MAJOR SPOILER]
Of course, he wasn't the most dangerous thing in the jungle. There were a lot of well-drawn creatures lurking. That's the second reason I feel that this film isn't so much completely original, but a mutation of a world we already know. The Tree of Life's seeds looked jellyfish. The Navi's land transportation were eight-legged horses. The largest land creature seemed to be a cross between a hammer-head shark and a rhino. My favorite was actually the panther-like creature that seemed to have a beetle shell. The Navi themselves were also incredibly beautiful, and—I don't know if it's because of the current vampire mania—but I loved that they had long, portruding canine teeth and Nightcrawler-like tails.