That only tells me you know little about how the synagogue system worked in the 2nd temple period. Those “uneducated” fishermen had the equivalent of at least a BA in theology by the time they reached adulthood. The gifted were already recognized by age 5 and removed to yeshivas to learn more extensively. (Like Paul)
Learning, education and literacy are not equivalent concepts. A person with no skill at reading or writing may have vast knowledge of theology as well as other things. We of the modern world tend to over emphasize the connection between literacy and knowledge and consider it impossible to become learned without being able to read until we meet someone that has become wise and knowledgeable without that skill. From some things I have recently read , I am not entirely sure that the synagogue system, though certainly in place at the time, was fully developed at the time of Jesus Resurrection. Paul's situation , as you point out, was not the norm but the exception that applied to the gifted. Nor was Paul native to the area that the 500 mostly came from as he is said to have been from Tarsus and not Judah so his background and upbringing would possibly differ from theirs in important ways. Of the 500, I would expect the majority to be illiterate. Now, just because I expect something to be the case does not make it so, but I have seen no clear evidence so convincing that I am moved to change my expectations .
This excerpt from Wikipedia disputes your contention. You may be correct and the author form Wikipedia be mistaken but I do not see that you have proven your case. I am not claiming that Wiki is correct, I am simply skeptical of what you have claimed based upon a small bit of research that I have done into literacy rates in the 1st Century.
Literacy[edit]
Despite this schooling system, many children did not learn to read and write. It has been estimated that at least 90 percent of the Jewish population of Roman Palestine in the first centuries CE could merely write their own name or not write and read at all,
[2] or that the literacy rate was about 3 percent.
[3] Exact literacy rates among ancient Jews in Roman Palestine cannot be determined
[4]
If you wish to convince me that your argument is the better one, which perhaps does not interest you to do, I ask that you present to me some better evidence that substantiates your claim than I have seen so far.