Stephenie Meyer by her own description knew absolutely nothing about vampires when she started writing and did zero research. I doubt that she had any idea where werewolf legends came from. That said, there are some Native American stories that are very similar to werewolves. The idea of a "skinwalker" shows up in some cultures, and the Navajo especially have a developed set of myths that has some resemblance. So if one felt a need to retcon this one would explain it with the natives simply using "werewolf" as the common English term for what they were.

(One could imagine fanfic where some of the werewolves are unhappy with this term and see using it as buying into European cultural imperialism or something like that.)