Even if you say Buddhism in a nutshell, it can be roughly divided into two currents: [Theravada] and [Mahayana]. Theravada Buddhism, which is still worshipped in Southeast Asia, etc., is so-called “old-fashioned” Buddhism, and the only principal image that is the object of worship is Buddha. On the other hand, as you know, many characters appear in Mahayana Buddhism.
For example, if the Theravada department ranges from compulsory education to higher education, then Mahaya is a university's faculty of education. In other words, until high school, you learn how to solve problems, and in the Faculty of Education, you learn how to “teach” how to solve problems.” As for the contents of “teaching methods,” of course, there is a learning system called how to solve problems that are easy to understand, and there is also a student guidance system that encourages and comforts students who are about to get frustrated and guide students who run delinquent to the right path. However, there are many differences among students, and there will be good kids, bad kids, normal kids, and children who fall behind if you teach everyone the same way. Therefore, we must prepare textbooks, reference materials, and study courses according to each ability and situation, and devise ways so that everyone can graduate safely.
In other words, in order for the students (sentient beings) to properly graduate (liberate), it was necessary to prepare a variety of teachers (Buddha, Bodhisattva, Myō, Tenshi), textbooks (sutras), and study courses (religious denominations) that were perfect for each level and type.