Therefore whether it were I or they, so we preach, and so ye believed. Whether it were I or they - All the apostles of Christ agree in the same doctrines; we all preach one and the same thing; and, as we preached, so ye believed; having received from us the true apostolical faith, that Jesus died for our sins, and rose again for our justification; and that his resurrection is the pledge and proof of ours. Whoever teaches contrary to this does not preach the true apostolic doctrine.
Paul was the last of the primitive apostles. The primitive apostles were those who had seen Christ, and got their call to the apostolate immediately from himself. There were many apostles after this time, but they were all secondary; they had a Divine call, but it was internal, and never accompanied by any vision or external demonstration of that Christ who had been manifested in the flesh.