Y'know why that depresses me? Because there ARE NO SUPERHEROES
Depends on your definition of superhero I suppose. Those who risk their lives to save others from certain death and/or disaster, in many cases without being certain their effort will succeed, certainly qualify in my book: Firemen (and women of course), medics in wartorn countries, disaster relief specialists.
We haven't seen disasters on the scale of comics, or at least not many that weren't happening before humanity came along (volcanic eruptions, tsunami, flash floods etc), so far Earth appears to be 100% alien invasion free, for example. But we are more numerous, and living in area's most sane species would never choose to live in (Anyone whose home is built in a flood basin for start) and are better connected communications wise, so we are simply more AWARE of the disasters which can befall us.