the confession or revelation that Jesus was the Christ, the son of the living God was the rock upon which the church would be founded. "for this was not revealed to you by flesh and blood, but by my Father in heaven." It is founded on the revelation, given by the Father.
1 Corinthians 12:3
3 Therefore I inform you that no one who is speaking by the Spirit of God says, “Jesus be cursed,” and no one can say, “Jesus is Lord,” except by the Holy Spirit.
Take a look at the Gospel of John, Chapter 1, the calling of Peter and Nathaniel to be disciples -
40 Andrew, Simon Peter’s brother, was one of the two who heard what John had said and who had followed Jesus. 41 The first thing Andrew did was to find his brother Simon and tell him, “We have found the Messiah” (that is, the Christ). 42 And he brought him to Jesus.*
...
49 Then Nathanael declared, “Rabbi, you are the Son of God; you are the king of Israel.”
50 Jesus said, “You believe because I told you I saw you under the fig tree. You will see greater things than that.” 51 He then added, “Very truly I tell you, you will see ‘heaven open, and the angels of God ascending and descending on’ the Son of Man.”
So Peter's personal declaration hardly seems to be unique, or the first person this was revealed to.
*By the way, if anyone wants to reconcile this introduction of Peter to Jesus (John 1:40-42) with Matthew's introduction of Peter to Jesus (Matthew 4:18-20), I am all ears. Feel free to contort yourselves as much as necessary