Are men naturally indifferent to each other?
I don’t think so. It’s evidenced that they’re not in that societies and such are constructed by people resulting in better living conditions that anyone would have if everyone was indifferent to everyone else. Maybe we don’t like each other for the right reasons, but we get along and help one another out because the world is a better place with us doing that than it is if we all fight one another. Good deeds even done out of selfishness are still good in a way.
Good deeds are bartered for good deeds.