"And Miriam the prophetess, the sister of Aaron, took a timbrel in her hand; and all of the women went out after her with timbrels and with dances. And Miriam answered them [ the song of Moses and the people which proceeded this] , Sing ye to the Lord, he hath triumphed gloriously; the horse and his rider hath he thrown into the sea..."
"Call and response" is an ancient form of music and ritual from a time before written lyrics, prayers, or formula, that is retained to this day in many traditions.
The significance of Miriam is born out as being called one of the prophets sent by God in Micah 6:4.
There is no evidence, as some fringe elements have suggested, that she was a priestess in Egypt, anymore than Moses was a priest. There is no evidence that her failure with Aaron of trusting to God's choice of Moses in all things was held to her account all of her life. She was strucj with leprosy as a result. This seems to not be intended as an unredeemable act. In fact, it appears that the people waited on her healing before moving forward. These seem to indicate that she was in all things just what the Bible calls her: a prophetess, a leader, and a woman of God.