A hero is an individual who travels into the threatening unknown, learns how to deal with the threat and defeat the danger, and then brings that knowledge and experience home to share with his community so that they are not at risk from that danger.
Sounds simple, doesn't it? Sounds 'Obvious', so obvious that it's simply stating something you knew already.
That's because you did know already. It's a very successful idea. The idea worked so well as a survival strategy - and our ancestors came up with the story idea so long ago - that it's written into our genes by selective evolution.
The idea worked. The idea of the hero still works. But only if the hero comes home and shares the idea... otherwise the hero put himself at risk for no gain to the species, and what's the point of that?
This is not my idea. I was introduced to the idea by someone who understood it far more thoroughly than I do. It was not his idea either. I think this is an idea so old that when the idea was expressed in a story we couldn't yet write it down, a time when our species was so surrounded by threats that we were failing as a species. If we had not come up with this idea and built it into our culture we would not have survived long enough to invent writing so that we could write the idea down. It's a bloody good idea, obviously. We survived, and thrived, and we have so few threats that we seem to have to make up threats or be the threat to ourselves (maybe just so we can challenge a threat and sate our genetic desire to be a hero and enact our generic heritage).
Yet, e still need heroes. Maybe specifically because we have forgotten why we need them. A threat, to expand just a little, can be an idea - a bad idea, an idea that destroys cultures and economies and people.
It can also be a lapsed good idea, or even a forgotten good idea, an idea that promotes the desire to defend a culture that protects the individuals of the culture from self-destruction because people no longer explicitly teach their children about what a good idea they once had about how exactly to keep society and themselves from self-destruction. That's an important gain from a hero who took risks to learn how to deal with a threat and share the idea with others.
As an example, Richard Dreyfuss reminds us of a neglected good idea:
And if you agree with him, go to the link and sign the petition.
As an aside, it might be worth thinking about taking the good idea home in a more explicit fashion than has so far been the case. Some people are still waiting for you.