Even if those things are real mummies of actually once-living things, there's nothing really connecting them with flying objects/USOs/UAP of any kind. They're just bodies from a mine.

They could represent creatures from an unknown subterrestrial ecosystem. Not exactly Hollow Earth, just deep-cave creatures that occasionally come up that split off hundreds of millions of years ago. They don't even have to be technological at all.

Hell, they look/sound like shell-less turtles.