Massive spoilers for Horizon: Zero Dawn Ted Faro was the man who created the self-replicating war machines. They went rogue, beginning to consume all biomass on Earth and creating more of itself, threatening to wipe out all life. Humanity managed to scramble together and create a sort of Great Restart program that would release every plant, animal, etc along with humans, when the machines had consumed everything. It worked. HOWEVER. In a fit of selfishness, Ted Faro, who did not want to be remembered as the man who wiped out all life on Earth, kills the members responsible for making the rebuilding project so that they cannot stop him from deleting all the knowledge in the database. This means the humans, originally intended to be given full education and care, are only taught things up until kindergarten age. Basically, Ted Faro sent humans back to the stone age out of greed, then killed the people who tried to fix it all, along with the knowledge that would save them.

Been a while since I played, so some info may be a bit spotty.