Yes, it seems to me that Peter (the “rock”) was the somewhat reluctant leader of the Twelve, but it became natural to attribute to him the role of primacy in the Church. Since the gospel of Matthew probably reached its present form (less any discrepancies due to copying), in the years 80-90, by that time the Church had probably established Peter as the primary leader of the Church. Paul seems to say this as well in some of his epistles.
The Canon is a declaration of the Church, inspired by the Holy Spirit, as to what books were inspired, and to be used in the Church for teaching. We can be curious about why some books are in the Canon (2 Peter) or why others called apocrypha were not, even thought they do not contain any obvious heretical teaching (the Didiache).
Of course, some today would challenge the Canon, primarily to advance an agenda hostile to the Church.
So, full circle - the Church “left to us by Christ” is divinely inspired, but humanly created and maintained… and thus flawed. Faith in Jesus leads us to a faith in the Church, as the imperfect carrier of His mission… which to me is plenty proof of His mercy and compassion.