What is your question?:
When John was baptizing with water, as I read it, he was baptizing to eventually reveal Jesus. But for those other than Jesus whom he baptized, what was the purpose of it, or how were they supposed to be changed by it?

The answer for this question:
Thanks for the question! Actually, many groups practiced baptism before the coming of Jesus. Jesus’ cousin, John, was only one such person.

The different groups that practiced baptism did so as an act of purification, to make oneself clean to engage in temple ceremonies. The act of baptism – or washing – showed an inner disposition for change, for purification. Fr. Bob