Yeah, I can definitely relate to Spider-Man, who's so nerdy that nobody likes him, yet who inexplicably has his pick of big-tittied girls who all want to sleep with him for some reason. That's so relatable. I think it happened to me last week.
I've said it before and I'll say it as often as I have to. The idea that Superman is not a relatable character is BS. He might not be especially relatable to teenagers, who might see more of themselves in Spider-Man or Batman (characters with a bad case of adolescent arrested development), but Superman is a character who relates more to the struggles of adults who have gone out to make their way in the world. Superman is what comes after you put down your silly "me against the world" mentality and adopt a less self-centered worldview.
When you lose a loved one, blaming yourself and bettering yourself out of guilt is Spider-Man. Feeling wronged and bettering yourself out of a need to lash out is Batman. Reflecting on the positive aspects of the one you loved and bettering yourself by emulating them is Superman.
And there's the very basic routine of how he conducts his life. Superman isn't a rich guy with a huge house and lots of cars. He's not a nerdy teenager who inexplicably has a dream job and lots of big-breasted female suitors. He goes to work. He has a good friend at the office, a boss with whom he shares an unspoken mutual respect, and a female coworker for whom he pines. His whole life is one of labors for the benefit of the world around him--not to sate personal guilt, get revenge, or anything silly like that--which is very much a working class thing.
It has nothing to do with power level, either. Saying you identify with Spider-Man more because he's less powerful is like saying you identify with MJ more because Shaq is taller.