I'm definitely with you on the aspects of survival instincts and adaption. Even though there is some social component there, such as the small groups early humans were a part of, there was still great concern from both other humans and other dangers such as predators.
Would you say that fear is a driving factor in the neglect and 'horrible historical figure' cases you mentioned? I.e. trying to make sure those traumatizing experiences don't happen again, or maybe more of a getting back at those who 'wronged them?' This isn't meant as an argument to you points, just looking at 'how it made sense to the person' side of things. I tend to believe we all do things for some (subjectively logical) reason, even if purely on a subconscious level.