I just heard a rumor on these forums that there was originally supposed to be three different story lines, one for each of the races. Bungie apparently cut the Awoken and Human races out and went with the Exo for all races. It kind of makes sense because how would a ghost revive a human or awoken that had been dead for many years? An Exo would make sense because it is a machine. Also, it doesn't make much sense to have different races purely for cosmetic reason? If anyone has any information let me know if anyone has any thoughts post them.