Surely putting imaginary characters in an imaginary setting can only result in stories limited by the authors imagination. If the author does not know all that

Surely putting imaginary characters in an imaginary setting can only result in stories limited by the authors imagination. If the author does not know all that much about human nature in the first place, only unrealistic stories will be the outcome. Worse, as a reader it is not possible to discern realistic behavior unless you already understand human nature, which makes literature somewhat useless for learning about it. I would argue that understanding of human nature is a necessary (but not sufficient) element of becoming a good writer, but writing in itself is not necessarily a good way to learn about human nature. As an aside, I'm a bit weirded out by the idea that reading books would be the best way to learn about human nature as opposed to going "out there" and interacting with people.