Threaten someone with the banana gun - EverydayHero to the rescue

How do you actually define a hero?
Is it an everyday-hero who picks up your wallet when you drop it, so you won't lose it, or is it firefighters, who save people from burning buildings and save lives?
Or is it those in the movies. They have super powers, they're invincible, strong and almighty?

The meaning of the word 'hero', depends on what that one person have done.
Let's say you save someone from drowning, pulls up the person from the water, gives mouth to mouth and saves a life, the person wakes up and calls you a hero for saving his/her life.
Or is that a saviour? You just saved someone from dying. Savior or hero?
Nowdays, we know that there is nothing supernatural, there's no superheroes in the world, no one can fly.
So the question remains: Who is a hero?

I'd say that everyone is a hero, it's just that there will always be someone better.