I agree with the previous posts about the significance of the name change as compared to other times in the bible is important to contemplate.(if you are inferring the primacy of Peter)
Also the Aramaic “Kepha” blows the Greek “Petra” vs “petros” argument out of the conversation.
As for the name change, the rest of the verse needs to be considered fully in its context. Especially when you compare it to Isaiah 22: 20-23 and historical context around which the old kingdoms (this one being David’s) were governed when the king was not there. It would be clear that Jesus and the rest of the disciples knew the OT and the significance of kingdom chain of command and realized that Jesus was commissioning Peter in a special way.
Now as why Kepha (Rock) and not something else? (marble, Stone etc) you got me.
My experience with Protestants is they do not put much weight around it because they think the church was built around the faith of his statement and he, Peter, wasn’t the originator of the statement but God.