Assume the premise is correct. Jesus spoke Aramaic. Kepha. Rock.
Ok. So what?
Grant that Peter held a leadership role among the Apostles. Fine. The claim Rome actually needs is bigger: Peter was the first bishop of Rome. The evidence says otherwise.
1. The Roman church existed before any apostle arrived. Paul writes to them around AD 57 and says their faith is proclaimed in all the world (Rom 1:8). He has longed to visit "for many years" (Rom 15:23). When he finally lands, Roman believers travel 40+ miles to meet him (Acts 28:15).
2. Paul got there first. "He lived there two whole years at his own expense, and welcomed all who came to him, proclaiming the kingdom of God and teaching about the Lord Jesus Christ with all boldness and without hindrance." (Acts 28:30-31). Documented apostolic ministry in Rome before any text places Peter there.
3. Peter is missing right where he should be. Romans 16 greets about 26 people by name. No Peter. If he'd been leading that church since the 40s, Paul skipped the most important man in the room.
4. The Jews of Rome had never heard the gospel explained. Three days after Paul arrives, he meets Rome's Jewish leaders. They know the sect only as something "everywhere spoken against" and ask to hear his views. They spend a full day, morning till evening, hearing him argue from Moses and the Prophets (Acts 28:17-23). Peter was the apostle to the circumcision (Gal 2:7-8). Tradition has him in Rome since AD 42. Eighteen years in the city, and the synagogue leaders need a stranger in chains to explain what Christians believe?
5. The earliest succession list doesn't make Peter bishop. Irenaeus (Against Heresies 3.3.3) credits Peter AND Paul with founding the church, then says they handed the episcopate to Linus. Linus is first.
6. There was no single bishop to be. 1 Clement speaks of presbyters, plural. Ignatius names a bishop in every church he writes to except Rome. Catholic scholar Francis Sullivan concedes Rome was governed by a college of presbyters into the mid-2nd century.
Peter likely died in Rome. Grant that too. Dying in a city doesn't make you its first bishop.
Kepha proves Peter was a rock. It doesn't prove Rome was his chair.
Petros vs. petra sounds impressive until you realize Jesus was speaking Aramaic.
It’s the same word for Peter and Rock!