Hero as a label for the main character of a story is somewhat misnomered, or at least overrated in my opinion. The word hero implies someone with outstanding abilities, almost perfect in every way, even someone who doesn't include "mistake" in their vocabulary. "Nonsense!" I say. Who wants a main character with no possibility of error? With no chance of conflict? Or problems? There wouldn't be much of a plot with no conflict, no problems to solve, and no resolution. Besides, I need to relate to the main characters I'm reading about. Human flaws are essential as a part of that. And we as readers develop empathy for these flawed human beings. We cheer them on and hope they overcome their challenges.
So, what does all this mean to you as a writer? Well, during that constructive stage of your story, when you begin to mold your characters --who they are and what they will attempt to do, you should also think about what makes him or her human. It might be a weakness that's physical or emotional. Or perhaps it is something that has happened in his or her life that leaves the character frightened or conflicted. As the character moves through events in the story, trying to achieve his or her goal and confronting the conflict presented by the antagonist, the one with human flaws will have a greater challenge. Without flaws, the "perfect hero" would find the road ahead simple to travel. But we don't want the journey to be simple. That would be like watching our favorite team play their biggest rival, and the game ends up being a total blowout. No excitement in that, is there?
Remember: fiction portrays life and life is made up of humans. So, characters, in order to be human, should be flawed. It makes sense to me. I hope it makes sense to you.
This posting is brief, but it seemed worth stating. And if anyone has anything to add, I welcome your comments and words of wisdom :-)
P.S. A bit of advice I just picked up over on Coffee Shop discussion board from John....use your own flaws as a starting point. They are the ones you are most familiar with and might help create some pretty fantastic characters!