> at the age of 13, Michelangelo was apprenticed to Ghirlandaio. The next year, his father persuaded Ghirlandaio to pay Michelangelo as an artist, which was rare for someone that young
He was literally getting education in art. It is not like there was no structure.
The apprenticeship was after this was painted. Prior to engaging in formal training he largely ignored school and spend his time painting and seeking out other painters to learn from:
> As a young boy, Michelangelo was sent to the city of Florence to study grammar under the Humanist Francesco da Urbino. Michelangelo showed no interest in his schooling, preferring to copy paintings from churches and seek the company of other painters. [0]
You can search other sources and you'll find the same: prior to apprenticeship he was not formally enrolled in any form of art education.
> The apprenticeship was after this was painted. Prior to engaging in formal training he largely ignored school and spend his time painting and seeking out other painters to learn from:
He WAS in schooling and parents sent him to that city literally for education. And then he got into apprenticeship for a vocation that was well paid and supported back then.
He was very much dropped to school and squirmed there to the forced extend. And very much, boys of his age could slack on school work in variety of ways - they did not played videogames, but they did played games in little gangs of theirs, hanging around and generally wasting time to the extend adults allowed it.
Boys and girls who draw well, have talents and spend some freetime doing that exist. They usually learn from youtube (today equivalent of him meddling with artists). They may be put into extracurricular classes, but no one sane will put them into apprenticeship for art - because art is unlikely to feed you.
He was literally getting education in art. It is not like there was no structure.