Perhaps it would be wisdom for you to read some scholarship by people with out an interest in claiming the bible as theirs
The NT as a compilation of inspired writings existed during the apostolic time..even as they were being written..
Origen, born long before Hippo had all the books of the OT and the NT . Jerome actually used Origens greek NT to translate to Latin ...
Origen believed in Universal Salvation just as the Scripture alone teaches.
I'm not saying they didn't exist. I'm saying they weren't canonized for "all" the Church until centuries after they were written.