"We have supped full with heroes..."

Time out of mind strength and courage have been the theme of bards and romances; and from the story of Troy down to to-day, poetry has always chosen a soldier for a hero. I wonder is it because men are cowards in heart that they admire bravery so much, and place military valour so far beyond every other quality for reward and worship?

This passage from Thackeray's Vanity Fair makes me wonder what it is about the figure of the hero that makes him or her so very attractive. The hero - whether literary, romantic, filmic, or theatrical - nearly always manages to acquire the respect and even worship of his or her audience. Why?
Is a hero a hero because he or she is capable of doing something greater than the mere mortals in the audience? Is it because the hero lives in a world that is somehow more raw, more primitive, more visceral - a world that requires heroism in a way that ours (for all its violence and tragedy) does not? Do we respect and worship heroes because we believe they are better than we, or because we see ourselves in them?

I think, perhaps, the circumstances make the hero. In reality, heroes do things that must be done if we are to hold out hope for our species - hope in both the psychological and biological sense. If someone were incapable of risking their own life to save others, our species might die out due to excessive fear, but the presence of heroes also allows us to recognize the human capacity for ethical justice.
In literature, the circumstances are controlled in such a way that someone must become a hero or the story would fail. Certainly, some Post-Modern works attempt to argue that there are no heroes, yet they most often focus on an individual who manages to mean something or at least mean nothing (which itself means something). But the focus makes them heroic because they represent the public acknowledgement of the more unpleasant, boring, seedy, and even embarrassing sides of human nature. They are heroes because they are in the public eye, drawing its sympathy, and making us question our own purpose in relation to our own realities. We may not like them, but they force us to think of them as heroes (even as anti-heroes), nevertheless.
But heroes we respect, heroes we worship, Achilles, Odysseus, Buffy, Frodo, Aragorn, Harry Potter... they are heroes in a far more Classical sense. They are heroes because somehow they take elements of the average human being and make them greater, more powerful, longer lasting. They are not perfect, but neither are we. Their imperfections make them somehow greater for their flaws because we can see that they are capable of overcoming those flaws. Perfect heroes - Galahad the pure and lily-white - are irritating because we have no hope of becoming them. Not only that, but they do not - they cannot - belong in our world. Perfect heroes die tragically because they are "too good" to live among the corruption of reality.
I would rather be Percival any day. Maybe he doesn't always get the Grail, but he gets close enough to begin to understand it and he gets to go home at the end of the day.