That's kind of the theme that is being thrown around. In order to save humanity from the forest, one must become an Overlord to wield the Fruit of Knowledge but we are still left in the dark about all that. We are told there are only two choices that Kouta must make, save yourself or save humanity. Redyue was trying to make Kouta crack by showing him what he never wanted to see, being portrayed as a monster by his friends and humanity even though he is trying to help. We know from the very beginning that is all Kouta wants to do, he is a very selfless person. Redyue knew this and used it against him but end of failing. I feel there is much more to this than what is being laid out on the table.