Yeah I think the word superhero was coined because the world hero had changed. In the old days hero referred to adventurers like Hercules, King Arthur, and Robin Hood. But over the centuries the word shifted to anyone who goes above and beyond to help others. So we needed a new word to describe the larger then life colorful characters who fight monsters and evil.
Good point and when you think about it there have been a lot more superheroes in movies and TV shows than just ones based on comic books that most people count and I have said to you once before 'Buffy' fits the exact description of a superhero with super-strength, enhanced speed, enhanced healing and the ability to jump higher than most humans and jump from up high and land on her feet without hurting herself but they called her a slayer. There have been many other TV shows like that where the lead characters have had enhanced abilities and powers like 'Alias', 'Lost Girl', 'Fringe', 'True Blood', 'Dark Angel', 'Continuum' (Kiera in her CPS Suit), 'Dark Matter' etc all had lead characters that had special abilities. One thing I have noticed in movie and TV show adaptions is the lack of use of the term, supervillain and I might be wrong but I can't remember hearing any of the movies and TV shows in the past decade using that word and they only use 'villain' where in the comic books they call them supervillains.