In the 1st, 2nd, 3rd centuries - up until the split with the Orthodox, there was only one christian church - the Catholic Church. If you know otherwise, plese name them.
In the first 300 years of Christianity, there were a lot of local churches joined by common beliefs, although the differences between the church fathers indicate divisions were not unknown. However, history does not teach that all these churches answered to Rome. That didn’t occur until after 400, and was a source of considerable conflict.
Many divided early on.
“According to tradition the Coptic Orthodox Church is the Church of Alexandria which was established by Saint Mark the apostle and evangelist in the middle of the 1st century (approximately AD 42).[1] The head of the church and the See of Alexandria is the Pope of Alexandria and Patriarch of All Africa on the Holy See of Saint Mark, currently Pope Shenouda III.” The split occurred, I believe, in the 400s.
Now, who was right - the Roman church, or the Egyptian one? Both claim apostolic succession. So I guess it depends on which Pope you side with as to who the true, 2000 year old church is.
There were other splits as well. That is why the argument “The Catholic Church is the only 2000 year old church” strikes me as silly.