I wonder if there is a simpler story pattern that Destiny follows, just like most religious stories do. A hero is needed to save humanity, this hero (or savior), gives their life in the process, usually willingly. It is a good formula for a story that people will enjoy because of the acts of heroism and the ultimate good deed of giving your life for another. I think it is interesting that this formula for a story is so common. It shows that, as a species, us humans feel the need to experience heroic deeds and accomplishments. These usually come in the form of religious stories because the religion gives us something to believe in. So the story of the Traveler, on the surface at least, is that of a heroic entity giving it's life for us to survive, though I believe that the real story Bungie is telling is much more complex and engaging.