If we take literacy in this context to mean 'able to read and write and thus access history', then it should surely be understood that it is possible to be illiterate today while nevertheless 'osmosing' a lot of quasi-literate understanding of the world.

Whereas in the Bronze Age, they didn't have such devices as television, radio, cartoons, etc. - or at least, there was not as wide a distribution of illiterate-usable media among the illiterate then, as there are today.