We tend to equate ‘Protestantism’, with the Protestant Reformation. Protestantism is simply a name given to following the original Word of God as per the O/T and the N/T, without any specific doctrinal ‘add-ons’. In other words, as was preached unto us by Jesus Christ, the disciples, the apostles and the prophets.
Other than a small difference in the number of books included in the KJV Bible versus the RC Bible, they are basically the same. The major differences between the Christian faiths, stem from the doctrines and understanding/interpretation of the Holy Word. Other than this fact, can it not be said that both basic faiths started at the same time? Are they not basically originated from the same Word?