In the end it is not about Paul or about any of the other apostles. It is about the gospel message that they preach. Paul reminds the Corinthians that the same gospel message was preached by all the apostles, and that they themselves believed it (1 Corinthians 15:1). This reminder serves as a foundation for the admonition that follows.
11 Ainsi donc, que ce soit moi, que ce soient eux, voilà ce que nous prêchons, et c'est ce que vous avez cru.