What a long chapter!
I am impressed by Mary's Song. She knew her Old Testament Scriptures. And, she knew how they connected to her Son. One of the facets of her virtue and righteousness is her knowledge of the Scriptures.
Zechariah's song of praise, likewise, was full of Scripture. What was going on with these babies was a Bible thing if it was anything!
In the womb, John jumped for joy. I wonder how Elizabeth knew that joy motivated him?