The way that some of these superheroes survive in the 8-16 bit games is that, even though they, or one can be reduced to low health, it is not completely annihilated. Some are even converted to non-human entities. It's very confusing to understand in visual aspects, but the sprites can be compressed and decompressed to work even in 32-bit or 64-bit graphics.
"I have no cash, but at least the memory of my computer operates efficiently." - Alan Turing