There are quite a few cryptids that use mimicry as a lure throughout different cultures, regions, and religions. Which one this OP ran into would mostly have to be narrowed down by giving a location and finding the cryptid that fit that area. It could be a fleshgait, a mimic, a skinwaller, a windigo or something else entirely.

According to pre-human and early human accounts, these beings have been around far longer than we have and will almost definitely be here far after us as well. Being that cryptids are still living beings in a sense, they're able to evolve to adapt to the environments around them and where they hunt (and also how they hunt).