Or just folks, y'know, people with conflicting impulses and personal goals and problems and degrees of idealism and needs.
Each "hero" exists in a network of people and situations, just like the rest of us, and what they decide to do, or not do, is influenced by those factors in a realistic manner. Nikki, for example, doesn't have much in the way of higher goals. She has a kid and everything else is secondary to that. Claire has the most complicated life because she's a minor and because - oh, that would be spoilers for you Brits, I won't go there.
Hiro has the simplest life, but that's partly a choice on his part as we find out in the second half of the season - he's shaking off the normal complexities of life specifically in order to be a hero. The Petrelli brothers can't break out of the ties that bind them, but that's partly because one of them doesn't wish to. Suresh is earnest, dedicated, and in many important ways, clueless.
Yeah, it makes for a lot of jerking your attention back and forth, and there's a critical mass past which it would be a mistake to take it. But until that mass is reached, it has the relationship-appeal of good soap opera with the action-appeal of a good plot-based story. Very comic-booky, in fact.