During Italians exploration and revisition of the ancient
During the Middle Ages, there was a mentality that individuals should devote their lives to the church above everything. In that time education was exclusively based on religion. Many scholars were fixated on the idea that faith was more important than mind and reasoning. This situation changed when Renaissance thinkers split from medieval tradition and emphasized individual experience and materialistic approach to life instead of religious duties. This philosophy emerged due to Italians exploration and revisition of the ancient Roman and Greek texts and scriptures partly because they were surrounded by the remnants of Roman Empire and they have noticed the disastrous place Western culture has landed on.
They greatly expanded the ancient works and innovated new ideas. Intellectual people such as writers, sculptors, architects were valued in the society unlike Middle Age times. There was now a new world view called humanism which valued human beings and brought attention to the human magnificence in both physical and mental areas. Humanism also brought increased enthusiasm in exploring things and quest of knowledge.
Renaissance intellectuals at the time were in awe of these fresh ideas. Almost every instutition saw great changes and secular arrangements. Education saw improvements. Pupils were now separated by their age and skills. Art now was interested in human proportions and realistic aspects.
There was still some religious paintings but Renaissance artist mostly drew from and inspired by real life.