It is because the body also holds the memories. In technicality, you can say the infomation is stored in the brain, but the brain also has a "backup", which in this case os the soul.
Holy hell my head hurts from reading this. I understand all of it but the shortness of some of the bubbles made me stress. Felt too short, not coherent enough to be normal, but still understandable.
Page 38, I think there is a missing word for the top right side of the top right panel. "Spirits don't usually consume human" is ominous af. You really need to get a proofreader.
The description is literally a time paradox. The child is trying to stop the parents from coming together but if she manage to do it, she will cease to exist, which then loops back to the parents getting together, and then repeat.