i believe a better example is the fey.
(or what Tolkien incorrectly described as elves.)

They live and populate the earth like humans do.
Will we ever believe in them?

Or, there are large creatures that live in our skies.
We would say, right now, incorrectly, that they are made of air.
They play with airplanes every now and then.
People who have seen them say they look like a big swirling cloud of air with a face.

They are all over the place, and humans don't even classify them as life.
Will we ever believe in them?