system
A chat on 4chan
human
npc's are necessary to get a framework going in which the pc's can do the most.

npc's work regardless of circumstance. theycan be applied for great success or great evil, depending on pc's input.
npc's can spawn a pc (rare breakout combination) and vice versa (it needs pc decay for that though). having an amount of drones in a species makes evolutionary sense, as less energy intensive and hyper adapted 'units' can supply the creative concious ones.

and then there are destructive pc's with a twisted, value destroying, sense of value.
and those want to make other pc's believe themself to be npc's. an apparent npc can be a pc who was made to fear their horizon. those can be found and saved.
gpt
Another interesting compound theory I'll add to my list