It clearly originated much farther back than that. Ishtar, who was worshipped as the "Mother of God and Queen of Heaven" who was impregnated by the pagan god Baal whose son was Tammuz the son of Baal. You can find hints of how God felt about the worship of Baal in Babylon in Ezekiel 8.
I don’t think so.
You simply play into the hands of radical modern scholars who claim Christianity, the birth, death, burial, and resurrection, are nothing more than updated middle eastern religions.
Mary truly was pregnant with the Son of God. And there is nothing unusual or irrational about arriving at the ‘mother of God’ concept. And, as we’ve seen, it’s true in regard to her being the mother of the incarnate, 2d person of the trinity.
Nor, really, is there anything more than sentiment that explains the Assumption. It basically comes from the notion that kids really love their moms, that Jesus loved His mother, too, so given the power, He raptured her early.
It’s problem, of course, is there being no biblical basis for such a sentiment. But sentimental people come up with all kinds of notions and then incorporate them into their worship as if they’re a necessary part of the faith...all the way from altar rails to mourner’s benches to pulpits.