Questions: 

1. Are the backgrounds and the preparations of the prophet fixed?

2. Are all human beings the same or is there any superiority between them?

Answers:

In the name of Allah the merciful the most gracious

I do not know what you mean by the word  (background) of the prophet is fixed, but if you mean their subjective infallibility the answer is yes.  Except sometimes they do something’s which is not wise, and which does not hurt their infallibility as narrated from the book Alamul Huda  (TANZEEHUL ANBIYA). If not you can illustrate your meaning for me.

Peace be upon you,

According to your question, we can infer from the teachings of the Holy Quran and the holy prophet that God created everyone with different likes and differences and if God was to create everyone the same this would not be fair. And this will cause the system to break because having a system requires that there are differences. For example, if everyone was a doctor that would cause a problem for society, but as of now we do have others such as pilots, carpenters, and some are scholars and so on. The differences are what has brought about these kinds of professions. Therefore, God is the only one who knows the reality of these differences