I think your post goes to the point of who decides. On a macro level, is it the head of the denomination, congregation, convention, etc.? On the micro level, is it a pastor, preacher, priest, or the individual? The Bible gives at least two examples, such as Peter and Paul acting alone and the Apostles acting as a group.
I believe there is overlap. The Catholic model is the Church proposes a set of beliefs. A person must decide whether they accept the proposed beliefs. Thence forward, they are to trust the priests and bishops, as having been properly formed and instructed. Simultaneously, a person must develop their intellect in such they can know if a particular priest, bishop, etc is way off the mark.
Ultimately, it is up to the individual to decide what is right for their soul. They must choose what they believe is the truth, out of several competing versions. Without a well-formed conscious and intellect, a person may accept false doctrines.
Actually, I’d tweak your model. The, so to speak, skeletal kerygma is proposed, yes. But then things bubble up, like Paul’s teaching and eating with the nations. Then, when there’s a controversy a council or a pope decides which of the teachings or practices is okay and which not.
E.g.: Paul gives us a son of man + son of God terminology.But finally we need an Ephesus and Chalcedon to nail down a framework for understanding what Paul said.
Is that tweak okay?