Why did God choose peter to lead the church?

St. Peter became the leader of the early Church because Christ instituted him as the rock, upon which his Church would be built. Jesus told Peter, "You are Peter, and on this rock I will build my church, and the powers of death shall not prevail against it. I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven" (Mt 16:18-19). St. Peter was the recognized head of the Apostles. Although St. Paul was more active in the epistolary apostolate, he recognized the role of Cephas and his headship since after Paul's conversion, he sought out Peter in Jerusalem (Gal 1:18). The Gospel of John also stresses the primacy of Peter, since in John 21, Jesus tells Peter to feed his sheep. Peter is charged with the leadership of the flock and taking care of his sheep, and Jesus, the Good Shepherd, appoints Peter as shepherd in Jesus' absence. Peter realizes this, and calls Jesus the Chief Shepherd (1 Pet 5:1-4), telling his fellow elders to take care of the flock that they were charged with. The difference is that the flock that Jesus gave Peter was not limited by boundaries or time, and Peter received the charge to take care of Christ's flock by Christ in the flesh! Not all elders in the early Church could make that claim. Rock, as something permanent, does not just pass away, which is why the leadership of the Church fell to Peter's successor, and after he died, to his successor, all the way down to Pope Benedict XVI.