Imo, it's better to have witnesses write accounts of your actions than yourself. I think Jesus writing his own account of performing acts considered unearthly, quite vain. It would be akin to me writing an autobiography on how everybody's poop but mine stinks.
Anyone can say great things about themself. However, it's far more convincing if strangers, friends, enemies, etc say/write great things about you.
The difference between Middle Eastern thought and Western thought is that words come second to actions. People don't learn by words, they learn by example. People don't make choices based on words, they do so based on variations of examples in their lives.
Anyhow, as for illiteracy, I don't think such existed in Hebrew males. They all had to be able to do basic Torah reading. They could walk into a synagogue, read a verse, give a thought on it, and leave. Or get called upon to read a verse. Mass illiteracy is a Western trait (outside of ancient Rome and Greece). It was purposeful in those societies for control.
(Even the Ethiopian Philip wondered upon could read.)
