The rock that Jesus was talking about was the confession of who He really was, the petra (large rock ledge or foundation stone) in Matt. 16:18 hearkening back to the same use of the term by the Lord in Matthew 7:24-25,
"Therefore whosoever heareth these sayings of mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock."
The rock upon which the church was to built was the foundation stone of the truth about Jesus Christ, not on Peter as "the first pope."
But that is not what Jesus said. You are just making that up to support your man-made belief.