The early Christians didn’t have a Bible. The Bible as we know it today didn’t exist until about 400 AD; up until then there were over 250 works that claimed to be inspired. Today we know only 27 of them are accepted as inspired.
Besides, at that time only one in ten people could read so if God only wanted us to have a book to explain salvation; he should’ve waited until now to give it to us (though many parts of the world are still largely illiterate).
The early Christians had tradition, oral tradition, taught by the apostles, not the Bible. The Bible was born from that tradition; the sacred tradition of the Catholic Church, and the Holy Spirit who guided our bishops to select which writings were inspired and which were not.
The early Christians were Catholic.