Nothing in the Bible speaks of a vast population of Christians of antiquity that were neither Roman or Byzantine Catholic.
Through the majority of the Christian era, the vast majority of Christians have been either Roman or Byzantine Catholic.
That is simply historic fact. Despite how it rubs your anti-Catholic sensibilities the wrong way.
And nothing in the Bible speaks of a vast population of Christians of antiquity that were either Roman or Byzantine Catholic.
There is also indication that the apostle Thomas founded a church in India. Which would be another population of Christians in the first century.