Every conclusion rests on the premise that two individuals would be able to establish a stable breeding population that could eventually rival humanity. Unless Frankenstein’s monsters had like, magic self-shuffling extra resilient DNA, they’d likely inbreed themselves out of existence after a few generations, assuming they did not have ethical objections to that.
And anyway, if Frankenstein’s creation was reproductively capable, he would either be considered human or else fully hybridizable with humans, so worst case scenario his hypothetical kids would take human lovers and then, what, we’d have a little fresh big weird alchemical goth DNA mixed in with the giant pool of the human genome? No big deal. That is hardly “extinction”.
Small “fact”… Frankenstein created the “monsters” from human parts… Chock Full of human DNA. It wasn’t a new species he created, he just stumbled into an accident that bypassed mortality for A round.
The monster in the original book was created through alchemy, not through assembled parts taken from corpses. That detail was invented for the Boris Karloff movie.
