Easy: James remained in, and was martyred in Jerusalem. Peter traveled so that the Gentiles might hear the Gospel from him:
Acts 15:6-7
The apostles and the elders were gathered together to consider this matter. And
after there had been much debate, Peter rose and said to them,
“Brethren, you know that in the early days God made choice among you,
that by my mouth the Gentiles should hear the word of the gospel and
believe.
Peter rose, spoke and silenced the assembly. James made the proclamation. Also, we do not argue Peter’s primacy from any single verse. Rather…
The argument in the quote is a red herring. Jesus
was not speaking Greek. They incessantly argue small rock or pebble and
completely overlook the elephant: Jesus changed Simon bar-Jonah’s name.
He does that for a reason.
Peter is named 195 times in the NT. The closest is John “whom Jesus
loved” at just 29 times. All of the rest even less. Peter is always
named first, Judas last. Here is a partial list of unique aspects of Peter:
Jesus gave Peter the keys to the gates of Heaven.
Jesus declared Peter to the the rock.
Jesus made Peter shepherd (Feed my sheep).
Jesus told Peter only to strengthen his brothers
Jesus paid the Temple tax only for Himself and Peter.
Jesus preached from Peter’s boat.
Jesus told Peter to “Follow me” at the sea of Tiberias.
Jesus called only Peter to Him across the water.
Jesus predicted Peter’s three-fold denial.
Jesus predicted Peter’s repentance and three-fold affirmation.
Jesus prophesied only Peter’s death.
Jesus taught Peter forgiveness 70 times 7 times.
Jesus spoke only to Peter at Gethsemane.
Peter is always listed first.
Peter alone received the revelation of Jesus as Messiah.
Peter alone spoke at the Transfiguration.
Peter pointed out the withered fig tree.
At our Lord’s trial before Pilate, Peter and (John?) were “following Jesus”
Peter entered the empty tomb first - John deferring to him.
Peter decided the manner of replacing Judas.
Peter spoke for the eleven at the Pentecost.
Peter was released from prison by the Angel.
Peter spoke for the eleven before the Council.
Peter held sin bound to Ananias and Saphira.
Peter’s shadow healed.
Peter declared the sin of Simony.
Peter explained the salvation of the Gentiles to the Church at Jerusalem.
The Angel told Cornelius to call for Peter.
The Holy Spirit fell upon the Gentiles as Peter preached to them.
At the empty tomb, the Angel said, “Go tell His disciples, and Peter.”
Mary Magdalene ran to tell Peter and the beloved disciple.
The vision of all foods being clean was given only to Peter.
Peter’s words silence the first council in Jerusalem.
Peter alone received the revelation of the end of the world (elements melting).
Peter alone received the revelation of Christ’s descent to hell/sheol.
Paul went to Peter to affirm that his Gospel was not in vain.
And on and on and on.
So, one can deny that Peter was primary, but it takes an amazing
disregard of scripture and history to do so