You come doing a great job of following typical figures of the culture that are of great interest. Very good, @honeydue! your most illustrative references are of more recent literary or audiovisual manifestations, which you do very well and I thank you, because my knowledge of them is not so dedicated.
If I wanted to make some very brief notes. The mentor, who we can understand as a guide, advisor or consultant, is a figure of great interest in the history of culture, especially that of the Eastern Hemisphere, which would broadly include Greece. Emblematic are the Zen or Sufi masters of legends, tales and philosophy. In Greek mythology and literature a Tiresias or a Nestor; in philosophy Socrates or Aristotle. In the American lands, in the cultures of aboriginal roots it also appears (the "teachings of Don Juan" of the Mexican culture have been very diffused),
It is a figure typical of ancient communities and classical cultures, and through them passed into medieval times. It is no coincidence that the stories of the books or films to which alludes are linked in a certain way to cultural atmospheres of this type, or that imitate them.
Our contemporary world has devalued or displaced this figure; the closest thing to it is the educator or teacher and the psychologist or psychiatrist.
I remember two beloved films that are not as recent as the ones in which you quote that figure appears very well represented in the roles I allude to: Finding Forrester by Gus Van Sant and "Dangerous Minds" by John Smith.
Thank you for a beautiful post, @honeydue.