Humans are able to pass on an incredible amount of knowledge without the use of writing. There are oral, epic traditions 100s of years old that we only know about because they were eventually written down. People were able to do things like recite the Iliad from memory. I don't know about other ancient languages but the oldest Greek texts of significant length are all metrical poetry. We know and have scientific works that were written in meter. There are probably all sorts of things that were passed don't orally that we can't even imagine.
