I just finished a post about how New Age ideas, including belief that UFOs are alien craft, fit in with a larger Metaphysical religious tradition. Belief in fairies and folk magic (practiced by what are sometimes called "Cunning folk" in the British context) are often understood by scholars of religion to be connected with this same metaphysical religious tradition.

Belief in faeries obviously predates belief in UFOs as alien visitors by centuries. The folklorist and Anglican minister Robert Kirk was collecting a rich oral tradition about fairies in Scotland by the end of the seventeenth century. I know of no claims about alien visitors to Earth prior to the nineteenth century. The idea of alien spacecraft appearing is largely a post-World War II idea, which only appeared after the development of complex aviation technology and the popularization of the idea of spacecraft in science fiction.