The problem of low hit points on humans

[UninspiredName]

Yes, but Alexander the Great didn't survive those battles by taking a direct hit from a halberd or javelin, and didn't really turn the tide of battle (Aside from morale, I guess) by being on the frontlines. I half-think the guy had a lot of luck as well as his combat prowess that kept him alive.

And remember, even in most fantasy, a hero rarely manages to alter the outcome of a battle by killing a ton of enemies in pitched combat. Usually they use some sort of magic, use the terrain, (say, triggering a rockslide) or take out an enemy commander, usually the last of the three. Rarely do you get a hero that can stand up to even ten enemies on his own. I'll also point out that these heroes are also rarely targetted by hostile magic and that, when they are, it's frequently a struggle to survive.