Answer all of the questions I posed. Are you saying that the Nicean Creed had no part in defining the criteria upon which the Canon was established to bring you the Scripture that you say is exclusively authoritative?
Neither I nor you nor anyone else was there when all that was going on. All we have is the record of what happened. We do not know what specifically was going on in the minds of those making the decisions.
So, no. Any canon or creed or any statement of faith of a particular denomination, should be the criteria for determining what was considered Scripture. To do so otherwise is putting the wrong thing in pre-eminence. Scripture should never be subservient to anything.
For the believer, Scripture is canon and creed. Since we have Scripture, we don't need any statement of faith from a church to dictate our beliefs.