I think it's safe to say...at this point...that most of the classical monsters that appear in CV are not meant to be the "original" incarnations of those creatures (Frankenstein, Medusa, the mermen.......hell, Dracula himself). We really shouldn't be trying to tie these Castlevania versions in with their literature/mythical/cinematic versions as part of the same canon. We're still dealing with the messy aftermath of Bram Stoker's story being dragged......kicking and screaming.....into Castlevania's continuity.