It was not just the bishop of Rome, the decisions for the Church were made by the gatherings of bishops local or universal like the First Ecumenical Council in Nicea (A.D. 325)
In this Council the heresy of Arianism was condemned and the true Orthodox Catholic doctrine about Divinity of Christ with His eternity and co-substantiality with the Father was asserted.
The authority of bishops is derived from the Apostles as the latter appointed their successors having the power to do so given directly by Christ.
From the beginning the Apostles and bishops met in councils when the decisions applying to the whole Church were needed. Their meetings were orderly and there was hierarchy of primacy among them. That is where the position ancient patriarchates and see of Rome is derived from.
This constitution of the Church lasted until Great Schism of XI-th century when the Western Latin Church and Eastern Greek Church separated. From that time in the Western Church the primacy of bishop of Rome became more prominent and explicit, in the East the more collective decentralized order prevailed.
With the invention of printing press it became possible to provide the books of Holy Scripture to the mass audience. So Luther and Calvin were able to undertake the reform of the Western Church by basing the reformed Christianity on the individual reading and interpretation of the Bible.
With the development of Congregationalism the principle of democracy and the autonomy of the congregation was established. This is not what was present in the ancient times.
Thankfully, that is not the only historical view and interpretation.