Question

Hi, greetings to my esteemed Michi 
 
Recently I started thinking about a basic question that, for some reason, had never bothered me until now.
I always thought of idol worshipers as pagan and primitive people, and monotheism as enlightened and advanced.
But on second thought, although it is clear to me that there is one God—that is, it is clear that in an infinite regress we will arrive at some kind of unity that cannot be defined, but it is one.
However, just as it seems reasonable to us that God created us, human beings, with the capacity for choice and intellectual and practical independence, why is it not reasonable that there are beings greater than we are (spiritually, perhaps angels, etc.) who have the capacity for choice just like us? And each of them does as he wishes. He can be wicked, a liar, lustful, etc. Just as Hitler, by his own choice, was able to burn millions of Jews in gas chambers (the Or HaChaim writes that even if it was not decreed that a person should die, he may still be killed by someone with free choice who decides to kill him).
By the way, this was awakened in me בעקבות a book (by Amos Oz) that describes the period before the establishment of the State. And the miraculous wonder in its establishment (economically, militarily, politically). And considering what happened a few years earlier to the Jewish people, I got the feeling that there are opposing forces here (one in our favor and the other against us…) and each time one of them wins…
 
It is clear to me that this is a conspiracy theory; the question is why this is more of a conspiracy than monotheism.?
 
In short, is monotheism true because it was given at Mount Sinai, or because it is philosophically rational?
 
(Maimonides describes Abraham's monotheism as a philosophical insight