Exactly. They were contemporary LETTERS between people and meant for instructions.who="Anthony MN" St. Paul wrote around AD 58 that the faith of the Church at Rome was renowned throughout the world. This means it was well established before much of the NT was penned.
The Church at Rome was a Christian church...not a Catholic one.
So you think that the disciples and Paul did no writing until they were near death, or even after death??? Their words prove different.
And sport but common sense tells us they were,probably copied and sent to other churches.And probably sent to Apostles,in Rome and other places They were held in reverence. And did nit just magically turn up 400 years later to be compiled by the Church of the Roman Empire.