Catch-21.95, the dilemma of cavespeak

What exactly makes a word or phrase “too modern” to be used by a resident of the Pleistocene? Can anyone give me a nice concise accurate dictionary of caveman-speak?

I don’t think so.

I am constantly amazed at how one person after another can pick out dozens of “wrong” words — and no two lists are anything alike. Each reader has a unique set of pet peeves. Most of it is from (IMHO) expectation based on assumptions ingrained by exposure to Hollywood crap. Movie cavemen must talk like cavemen. Pile it on, grind it in. They are dumb savages, right?

Wrong. They are our ancestors, and they were some damn smart cookies. They created works of art that put goosebumps all over modern viewers. They were human beings who concerned themselves with food, hunting, survival, what the neighbors were up to, and why the stars stuck to the sky. They had rich, complex language that we can only guess at from root words that survived in many modern tongues.

So, why is it wrong to interpret their (fictitious) thoughts in words that come as close as possible to what they intend to say?

Every word that I use to write is modern English. Where do I draw the line? And then there’s the other side of the coin. My vocabulary is large and eclectic. It isn’t limited to what some people hear on TV. Is it all right to use a word that Shakespeare liked?

Just gimme a clue.