How did early humans (think cavemen) learn their culture? could they read it in books? were these people what we would now consider "literate"?

They couldn't learn it in books because first systems of writing were established later during early civilizations around river valleys. Cavemen taught their culture to other orally. Considering what falls under today's standards as literacy, they were highly illiterate because even their speaking was not unique, let alone reading or writing that didn't even exist.