During the 1950s, one subset of UFO phenomena were "contactees" who claimed tomeet humanoids from Venus and Mars and were taken on tours of the solar system.

Now look at the Vrill story which predates UFOs (but mysterious airships were around) and the stories sound like the contactees.

The contactees today are the members of the Disclosure Project run by Greer.

Now John Keel and Dr. Jacques Vallee promoted the alternative to the extraterrestrial hypothesis which is called the interdimensional hypothesis that entities from an alternate dimension even time travel to this present Earth reality.

Vallee compares Celtic myths and odd tales and pictures presuming that these interdimensional visitors also contacted those folks who believed in fairie folks.

Vallee believes these interdimensional visitors are trying to manipulate cultures through myth and religion.

There are also theories the visitors come from a broken reality and are androids gathering data so they can repair their timeline by determing when things went awry.

Keel and others felt there were thin places, an older Irish belief, where realities blurred and merged. He thought that even species like Bigfoot and the Mothman and those giant wolves from Skywalker ranch transferred into our reality.