I guess it can seem like God has changed when going from the Old Testament to the New Testament. Probably what happened was that God remained the same but that we changed!
As times were more primitive, it seemed God responded to us differently, perhaps in a way we would understand. Now, we are in different times, and he has progressively been revealing more and more of himself over thousands of years. In the past, there was more we could not understand.
God seemed to tolerate different sets of norms. People in the Old Testament sometimes had more than one wife, and that was considered fine up to a point. People were stoned over what would be considered now to be minor infractions.
Noah seemed to have drunk too much one time, and he was not blamed for it. At that time, that was an acceptable way of trying to get closer to God.
Old wine, old wine skins. New wine, new wine skins …Old Testament and its rules, New Testament and its ways and rules.