The correct answer to this open question is the following.
Although your question does not include further context or references, we can answer it in general terms.
The people involved in teaching are, of course, teachers, the principal, the board of directors, administrative assistants, the school district, and the Department of Education.
We can also consider extracurricular activities such as Athletics, and Art.
Without a doubt, the school teacher plays the most important role because he/she is there, in front of the class, playing different roles such as educators, leaders, role models, and tutors.
Teachers are responsible to stimulate critical thinking and planning positive discussions to stimulate the ideas in the brain of the students and encourage them to express their opinions in the correct way.