Also, Gandalf is a Maiar, a supernatural being. He's not a human, or a human stand-in such as a hobbit.

If I build a battle robot and the robot goes to battle, is it a hero?

Are angels heroes?

It's a near-universal trope of superhero comics that heroes can't lead normal lives and that when they do, they're inevitably reminded of the inherent dangers, e.g. perfect hostages in the form of their loved ones.

"Normal life" is a relative term. I can think of few superheroes who are in a situation analogous to what was described by emr above with respect to Eliezer's consort. There are certainly individual obstacles that superheroes face that normal people don't, but the overall effect of these obstacles on the superhero's life is limited, even if they loom large in an individual story.