Am I the only one that now wants to hear the story of the second Avatar? In a way I find that more interesting because it's the first re-incarnation. There would be no system set-up to identify and train the Avatar. He or she would have had to have discovered their true nature on their own, retrain in all the elements and convince the world that they are Wan reborn. This is probably the same incarnation that set up the temples and the statues.
Actually, now that I think about it, why do those statues glow? Are they tied to Raava somehow, or is it the site those temples are built on that has the connection?