Why do y’all want Peter for your rock to build your church on instead of Jesus?
No one has said anything about "instead of." The point is that Jesus gives to Peter a name that indicates an association with Jesus Himself. Peter is a "rock" on account of the special purpose God has now designated for him. And the notion of Peter being a foundation is consistent with what Paul writes in Eph. 2:19-20 in speaking of the "household of God" being built upon the "foundation of the apostles and prophets."
Scripture speaks of persons being a foundation of the Church, even as it speaks of Jesus being the One foundation.
The change of name indicates a special role within that Apostolic foundation. Like with Abram becoming Abraham, it designates a special association with God's plan. And Abraham, by the way, was also termed a "rock:"
“Hearken to me, you who pursue deliverance,
you who seek the Lord;
look to the rock from which you were hewn,
and to the quarry from which you were digged.
2 Look to Abraham your father
and to Sarah who bore you;
for when he was but one I called him,
and I blessed him and made him many. Is. 51:1-2
So Scripture calling Abraham "the rock" doesn't negate or change that Scripture refers to God as "rock." The same is true with Peter being called "Cephas" = "rock."