I would agree that the Incarnation is a great event in Christian history. But the action was solely God's-not man (or woman). INCARNATION GOD SENT HIS SON, TO SAVE US by J.I. Packer
Your statement indicates the incarnation hinged upon Mary-e.g since Mary did not walk away from infant Jesus this was all part of the Incarnation.
The Word became flesh and walked among us. Incarnation means "in flesh". So long as the Word was flesh, God was Incarnate. Had He become flesh and disappeared, Incarnation would have been one thing. But He didn't, so it means something quite different.
God could have chosen Jane, Agnus
Or a tree or a bug or HarleyD or no one at all. But He didn't. Jesus had a mother, her name was Mary.
Protestants view the Incarnation as strictly God's action.
So I see. What isn't God's action if we wish to look at it this way? Carried to the extreme, pretty soon we end up at the place where nothing we do matters or has any meaning. It's a clockwork universe and you and I and Mary are but interchangeable cogs. And somewhere along the way, all is sound and fury.
But God entered human history in a new and marvelous way. That Christ became Incarnate matters, how He became Incarnate matters. How He lived and what He did matters. What Mary did matters. What you and I do matters. The universe has meaning. It is infused with meaning in each moment of its creation.
Thanks for your reply.