I’m not fine with that, and here’s why. First, the world of Jesus and his disciples was illiterate and lived by oral transmission. Second, the writing of Matthew and especially Joh are just too urbane in their Greek for Galilean fishermen to have written them. Third, the dates are way too late — especially for John.
This "illiterate" business reminds me of the "poverty" myth.
Many of the people with Jesus were well-to-do or outright rich.
despite the Mother Teresa mentality people have about the
poor in the Gospels.
Same too with literacy. Well to do people were more likely
to be literate. John Zebedee's family seemed to be well off
and John wrote various letters - I doubt he needed a secretary
to do this.
Same with Peter and Andrew.
Someone wrote the Gospel of Luke and Acts together - no name
given but as these were copied and handed around people
would have identified them with someone - why invent a name
when all you have to do is use the name of the guy who
wrote them - he was known to many of the readers personally.
And Matthew was a tax official - knowing multiple languages
was well nigh compulsory for his job.
And of course - people who left all and went out into the Roman
world preaching would have taken the time to learn another
language, and how to write.