In Santiago's student-teacher relationships, what does he learn from each of his teachers (human, divine, animal, and natural)?
In Paulo Coehlo's book, "The Alchemist" our protagonist has many "teachers". Santiago learns lessons from everyone and everything he encounters on his journey, right down to the desert, the wind, the sun and even his own heart. To fully answer your question I would need to write an essay which is neither practical nor appropriate for this forum.
To briefly summarize Santiago's lessons he learns on his journey; he learns that everyone has dreams, but people's hearts are afraid to follow them because they might fail and this would cause them to suffer. If you do chooseto follow your dreams there is a cost to it, but the universe itself will help you to reach your goal. That you must learn to speak the Universal Language. That the "greatest lie" is that at some point we lose control of our lives and are simply along for the ride. And finally, that as we try to change our own lives we also change the world around us.
I hope that this very brief overview will point you in the right direction. These websites might also prove helpful to you on your journey :-)