How has the idea of Superheroes changed and how have superheroes changed?

Answer 1

At first superheroes were never morally ambiguous being altruistically motivated to do good and to be a both a benefit to society and their respective culture whereas in contrast the modern day 'superhero' is , at best , morally ambivalent [little different from an antagonistic antihero] seeking to impose their own agenda upon their world and environment . As examples see how the superhero myth was deconstructed by Alan Moore's "The Watchmen" and Pat Mills' "Marshal Law" where the 'heroes' are more problematic to the betterment of society .