Cave dweller

A cave dweller or caveman was a being inhabiting a cave. This was not uncommon in primitive cultures.

On ancient Earth, Troglodyte was a term for cave dwellers. 

The early Earth cartoon Daffy Duck and the Dinosaur showed a caveman and the cave he lived in. 

After being stranded on Hanon IV, USS Voyager crewmembers speculated that it's natives might be cave dwellers. 

Upon studying an Iconian device recovered from Denius III, Donald Varley described his frustration at not understanding it by comparing him to a caveman confronted with a Tricorder. 

Two decades after Dramia II was first hit by an Auroral plague, the once civilized planet again had cave dwellers.