Many people in ancient civilizations were trained in a mostly forgotten art, the recital of long stories, aka 'oral histories'. However, it's doubtful that any one person could retain a whole library of such oral histories, i.e. it was probably closer to one long text per person, given the limitations of human memory. Writing was essentially the creation of an external memory system that other people could refer to. For example, the first records of Icelandic sagas:

https://retrospectjournal.com/2016/10/10/from-oral-to-writte...