​How "Skinwalker" became a catch-all word for every cryptid or feral entity?

Hello everyone. Living in Italy, I'm geographically about as far from Navajo reservations as you can get. Yet, whenever I come across an unfamiliar term, I like to look it up, which is how I got a basic idea of what a Skinwalker actually is in Navajo tradition. ​What I find bizar...