Sorry thought of something else. Our Bodies Would Have Decomposed. Whatever the ghost and the traveler did to be able to bring us back to life they had to put us back together. Maybe they have the ability to reconstruct a brain but not reconstruct memories. Ooooo Ooooo or maybe they wiped our memories for a reason that will come up in future story. I can do this all day. The later theory I mentioned would go with theories I already have about the speaker.