As we can see by the first scene in the campaign, the Ghost has the ability to revive a dead person, robot, or Awoken, apparently it doesn't matter how old you were. The crucible, and the missions suggest that the Ghost can revive you as many times as I will, unless it itself is destroyed or the darkness eats the light in you....i think....so what about the others? What about the non-Guardian humans and Awoken? We've already seen that Awoken die. Is it possible that no one in the solar system actually knows the capabilities of a Ghost? If so, then why aren't all of them immortal? It seems that we've been pulling the wool over everyone's eyes, Awoken are dying, yet we have a means to live eternally? And if we can revive ourselves using our Ghosts, then how come humanity was in trouble in the first place?