I think you’re right! I think too that perhaps we can get a greater appreciation for the narrative’s estranging qualities when we consider its original audience…and how unknown Shelley’s narrative may have been for them.
Then again, was it THAT unknown? You’ve already referred to other creation myths. There’s also the Jewish folktale of the Golem…but this very well may have been the first time an author tried to explain a creation myth with science (even “vague” science!) Maybe that’s where the unknown truly came in.