Our hero gets a chance to be an Avatar, which means an incarnation of a god or spiritual essence. We could all take this lesson to heart and remember that each of us contains a part of Spirit, and it is our spiritual destiny to integrate our body and Spirit, which we do through connection to our soul.
Our hero, in connecting to his avatar body and to Pandora, learns the truth of the Celtic belief that the good king is wed to the Land to protect its health. (The Lion King has this story plot: once the evil Scar kills the rightful king, the land dies. We get the Wasteland.)
Avatar is the myth of the return of the King. This is another urgent demand of our times - we need men to take up their 'kingship' again and protect life, not create death in the service of the economy. The inner king has returned in many women, but we also need the feeling, intuitive queen to ground our energies. We need both men and women working as partners to use their energy and talent to reclaim our world before we destroy ourselves.
Avatar creates a holistic experience that touches our hearts, which is where we discover the truths of life. That's why people love it. Because it's realer than the mindless, soulless reality our modern corporate culture would have us live in.