The NPC's where flies or simple lifeforms in past lives
Take china for example which does believe in reincarnation.
Which is now putting laws in place telling citizens to stop reincarnating because of over population. lol
So if china is over-populating more than the amount of people dying then their souls would start diluting. So if the deathl/ife ratio for example is 1/4th then when someone dies their soul splits into 4 parts to inhabit 4 bodies. Leaving the new person basically soulless.
And everyone claims chinese people have no souls. They practically act like NPCs over there.
I see videos from china all the time when people get run over in the streets and not a single one even stops to help the person. They don't even take their phones out to record it for youtube. They act like it's normal.
I don't believe in reincarnation personally. But if it's real I believe humans inhabit humans, dogs inhabit dogs, etc. But I do find it odd how the world is overpopulating and people are getting dumber and more soulless by each generation. We no longer have natural selection anymore to weed things out.