@knight_noble learning what?
He tried to save several of the people he was inhabiting, he even saved the lives of several other people...but he always ended up dying...often being tortured to death, or having to watch someone he loved die. Death told him from the very beginning she wasn't trying to teach him anything, she was just trying to fuck with him. If she wanted him to learn something, then she would have rewarded him when he tried to live instead of just going on toward death.
@MrMcNasty How did he have the ability to keep them from dying? We saw exactly the opposite in 65 chapters of this story. He tried multiple times, and it never worked....again...death said from the very beginning, there was no lesson.
If anything, the only thing he learned from this entire experience is that death is inevitable, and life is painful.