I suspect you of esoteric leanings from time to time. While what you write has appeal to people of an intellectual turn of mind, it is vital to remember that religion had to make sense to the dim-witted, criminal-minded layabouts who make up the bulk of human society.
In this context, we must differentiate between Mediterranean and desert cults. Judaism and Islam are desert cults, born out of a harsh environment where people were forced to work together for survival. Unity, loyalty and the tribe take precedence over the individual. There is no place for the individualist, the nonconformist -such people represent a threat to the whole tribe. The discipline requred is hierarchical and quasi-military in its nature. As an army can have only one Commander-in-Chief, so such a society can afford only one god. Disputes, or even different attitudes to life, are dangerous and must be quelled. The quarrelling gods must be united into one. Just as centuries later the Nazis created the idea of the Aryan race as fighting for survival, requiring the solution to be "Ein Volk, ein Reich, ein Fuhrer!" (One people, one realm, one leader).
The Mediterranean climate is far more forgiving, allowing not only survival, but, with a modicum of work, prosperity. It encourages settlement, leading to an agricultural surplus, which leads to specialisation. As the people specialise, so do their gods. Thus the numerous vegetation cults, with their dying and rising hero-gods. Also the smith-cults, the warrior-cults, the God-Kings and so forth. Diversity benefited the community and so was encouraged as a way of maintaining the essential functions of a more complex society.
Paul of Tarsus - an opportunist with an eye to the main chance - aimed to get rich by inventing a new mystery cult. A Hellenised Jew, he proposed a single god, as did the Stoics. He cooked up a judicious mix of Stoic thought and the teachings of an obscure itinerant Essene from Galilee who shared a (relatively common) given name with a Judaean Zealot who had got his silly self crucified some years before, and to make it appeal to his Mediterranean customers, added in a fairy tale about the prophet rising from the dead, like any other vegetation hero. I suspect he made a packet before his successors made the whole scam respectable!
Speculation, perhaps, but if studying history, psychology and sociology has taught me anything, it's that nothing ever gets started unless someone is getting something out of it - power or money and preferably both, usually.
In any event, it's clear that the openly polytheistic Roman Catholic Church owes more to the Mediterranean cults it displaced than to any Judaic origins. In turn, the Protestant Reformation owes more to the philosophical ideas of the Renaissance, with a more distant, less earthbound God and a more human Christ, as well as the idea that a Christian must work to his own salvation through study and good works, rather than blindly following rituals he didn't understand.
