bullethead
Of the hard cast variety
Yes, Arius - one priest in Alexandria - taught that. The church met at Nicea to refute him because that was not what the church had always taught.
No new doctrine came from Nicea. They were opposing Arius’ new doctrine.
Apparently Arius and whoever else under him spread around the empire did not get the universal memo or direct instructions from God and therefore taught how they understood it to be. That went on until the Council made the doctrine official, IE: adopted it.The first creed was adopted in A.D. 325 by a Council held at Nicaea.