Was thinking that if you wanted a meta origin you would have to exclude mad scientists.
Then, no, because you could ensure that mad scientists do not actually produce full scale heroes -- or villains, either. Just minions, perhaps. Throws out a lot of classic plots, but then, any constraint on the world limits the plot, and forms the essence of world-building. (How to carve a world: take a block of marble and carve away everything that doesn't look like your world.)
On the opposite hand, all of them could be the product of mad science. One common origin. Burning question about who the first one is, whether known to history or buried in the mists of time. But all sorts of superheroes and supervillains could be spawned that way -- also precluding a lot of classic plots, but not, I think, so many.
I wonder whether Girl Genius is the first type or the second. No flying bricks or the like, but some constructs come near some super characters.
Or mad scientist experiments could trigger whatever origin it was. Imagine a mad scientist in Wearing the Cloak. A bit more reliable than a vampire, since you could keep on experimenting when one thing didn't work, but since the breakthroughs you triggered would stem from the