Essays could be (and I presume have been) written on the artificial "other"ing of mutants in the Marvel universe, who are at the most basic level human. Suffice to say that's a different matter from the benevolent aliens, the literal gods-descended-from-on-high, ordinary people empowered by gifts from 5th-dimensional beings, etc. And yes, Luthor is a hypocrite. Does this surprise anyone?
I think the moderate view to take on superheroing is as analogous to parenting. I don't know of anyone who makes the argument that chidren are better off without parents at all, but by the same token, an overprotective parent can be as damaging, if not more, to a child's development as a neglectful one. A Superman who wards off Darkseid and saves people from burning buildings is good. A Superman who does everything from picking up every piece of litter to curing cancer is less positive, even if seeing Superman picking up litter or trying to cure cancer makes him that much more likeable.
The thing about humanity and limits is that we push them. Maybe not all of us individually, but as a species, we push and push at our limitations, and when we break through one, we get right to pushing at the new one past that. That's why limits are seen as so human, and those who can (or seemingly can) do anything are not. When a superhero does everything for us, we no longer have anything to push against, meaning we either lose a piece of our identity, or we find something else to push against (like said superhero).