Isn't it weird that he was in some modern ruins type deal as an abandoned child but it seemed like it was in the other world instead of his current modern life? Did the background guy mess up there or did I forget something about the lore of their past lives
looking back at the start of the manga - Godo wasn't a reincarnator to that other world, but was born, grew up, and died there, and
then was reincarnated into our world in Japan for this story.
It's kinda like an Isekai, only he started in the Sword & Sorcery Place, and then ended up in Mundane Japan Land.
So the flashback of him as a child in a burned out otherworld city, is correct, because he's originally from that world, not this one where the story's presently set.