I would argue that they didn't survive, unless they were predisposed to it. If you were depressed 500 years ago you died.
For those humans, at that time, who were mentally ill, I agree, they either died from exposure or were protected by other humans. That protection was expensive, though, and wasn't available to many families.
Actually it feels somewhat unfair, how hard it is to die, nowadays. You literally have to commit a violent act towards your body to do it.
I'd love to just sort of blamelessly die by exposure or something. No fault of mine and no fucking life on Earth, thank you very much.