It's when someone makes a fast and false conclusion because they only know the general idea of the thing they are concluding, and not all of the facts, if that makes sense. It's kind of like a stereotype, automatically assuming that someone is a certain way just because they participate in a certain sport, for example.
No. They're heroes in everyday life. You could call police officers heroes A hero is a person idolized for their courage.
Not sure who despereaux is? Harry potter yes
What? You have to ask a question! Nothing is being asked or anything.