I guess the issue here is about how you are defining 'superior.' If the argument is that mutants are in some way morally or ethically superior to non-mutants, absolutely not. And that is the source of a lot of the conflict in the comics. But in terms of what they can actually achieve in life, when you can do something like Magento does, you've got an inherent superiority.
Now I admit that you can't make that claim for all mutants. Not even all X-Men. I would not say that Cyclops' mutant power makes him an inherently superior human in terms of power because it severely limits him in many other ways and, if he wasn't on a team that regularly needed his power, would find life pretty difficult.
So I guess you can't argue that all mutants are superior, but many of the ones we see could basically rule all of humanity if they were allowed to get away with it.