Re: Gnostic stuff about Mary –
Marcion decided that none of the OT books, and none of the Gospels but Luke were true, because they all mentioned too much Jewish stuff, and his idea was that the Jewish God was the creator of everything evil, like matter and flesh. So he kept parts of Luke that only mentioned Gentile things, but he cut out everything about Jesus’ conception and birth. (In fact, he started his edited “Gospel of the Lord” in Chapter 3 of Luke.)
Marcion’s idea was that Jesus was never born; He descended from the heaven of the real God (ie, not that Jewish God) directly into Capernaum (because the Gospel says Jesus “came down into Capernaum”) and started preaching directly upon descent. No, I am not kidding.
There’s no wedding at Cana, either. The amusing bit is that Marcion then leaves in the part of Luke where he talks about Jesus’ mother and his brothers, even though Marcion’s whole spiel was that Jesus literally had no mother, brothers, or human relatives of any kind. Similarly, he leaves in “the womb that bore you,” for no logical reason. Marcion did leave in the Passion (a much shorter, de-Jewished version) and Resurrection, though. (Not sure how that fit into his heretical theology.)
Re: Manichaeans, their beliefs were mostly a mix of Zoroastrianism and Gnosticism. But there seem to have been some Manichaeans who mixed their stuff with Zurvanite Zoroastrianism. In one Parthian text, Mary is described as being perhaps an immortal goddess – namely, “the soul of the god Zurvan,” who was supposed to be the god of Time who was the father of both Ahura Mazda (the Zoroastrian god of goodness) and Angra Mainyu (the Zoroastrian god of evil). This Mary was “the Maiden of Light,” and “the head of all wisdom, who has enlightened all the gods.” She is also identified as one of the many gods and goddesses up in the Moon.
To the Manichaeans, “Jesus the Splendor” is important, but just one of the many Persian gods who come to earth in waves, to help with the salvation of man and the defeat of evil. (And basically, the closer to Persia, the more Manichaeanism was all about Persian gods. The further away you got, the more they turned into Greek-style abstractions like “The Great Mind.”) The Child Jesus, and the suffering Jesus, are not actually Jesus the Splendor, because gods can’t age or suffer like that. Instead, they are emanations of his mind.