What is a hero, exactly? Depending on who we are, we may define them in different ways. A kid idolizes his dad. Maybe his dad idolizes the star quarterback. This would be a good way to discuss “Unbreakable” (2000) if this were a college class on “movies as modern literature.” But it’s not. Instead, let’s focus on the fact that M. Night Shyamalan’s movies are mostly f’d up, with sinisterly twisted endings. This is no different. As a bonus, Bruce Willis walks through the entire film like a guy with a concussion. Or maybe it’s us who feel that way.