Did Jewish boys learn to read and write in the first century? I know they were educated.

Yes. That is very clear from the source quoted in the original responsa. The Talmud, Tractate Bava Bathra 21a, which praises the sage Joshua Ben Gamla (1st century CE) with the institution of formal Jewish education. Prior to this, parents taught their children informally. Ben Gamla instituted schools in every town and made education compulsory from the age of 6 or 7.