Actually, most regular humans do live on Lion Turtles. Or they used to. That only changed a few years ago. It's been really hard for most of them to build their homes from the ground up. Most had been living in cities that were centuries old and the only building that had been done was to repair what was already there.

And yes. That's right. The spirits that chose to stay are ones that believed they could help humanity learn and wanted to try. Some were ones that gave up their immortality and took on mortal forms. I'm really happy to have their help.