The priests (Cohens) and the Levites were engaged in teaching, educating, and serving the population. They did not sit and wait for people to come to receive a blessing; they traveled across the country, teaching people to read and write.
Therefore, there were no illiterate people in the nation of Israel. Since Moses received the Torah, everyone was obliged to study it. And the Jews received their literacy from Abraham after they had exited Babylon.
It was the absence of illiteracy that distinguished Jews from other peoples. It was believed that a man who did not teach his son makes him a thief.
Everyone had to know what laws are described in the Torah, how to implement them, and how to interact with other people. Jews studied the judicial system and the tax system because everyone had to participate in it.
Moreover, they had to implement the laws of the Torah not only on the internal level, but also in everyday life: the laws of kashrut, cultivation of the land, etc.
Jews knew the Torah, the Scriptures (Ketuvim), the Mishnah, and the Talmud by heart. They were inside each of them. They were taught to people without any textbooks, because only the Tanakh (Torah, Neviim, Ketuvim) were written on paper, and the rest were not.
This knowledge was a daily code of life for a person, and they knew how to interact with others. Therefore, the goal of priests and Levites was to educate everyone.
At the age of two, a child was taught the alphabet, at three – reading, at five -the Torah and the Mishnah, by nine he already knew all the laws, and by the age of 13 he had to know everything that he needs for life.
From KabTV’s “Secrets of the Eternal Book” 10/26/16