This is colonial thinking. “Civilization just happens to be the natural evolution of what I am doing. Your ways are barbarian backwards savagery”. It is the same logic.
There’s nothing natural or linear in religious belief. Catholicism itself is fragmented into hundreds of sects, and so is every single religion ever to have existed. Adapted to the particular capricious vanities of the local clergy and the established local customs. Christians taking some Jewish elements was just a manipulation tactic. I’m also sure some Islam sects would behead you for suggesting that Islam is a derivative of Christianity. The theory of a proto religion is also wrong, we know for a fact that not all of modern religions started from the same proto-belief, but ancient religions are actually quite varied and distinct.