Why stop at 26? Christ in verses 31-32 Christ singles out Peter to pay special attention to what he says next, then says Satan wants to sift him like wheat and tells Peter to strengthen his brothers. That is, to serve his brothers.
He tells Peter to serve his brothers right after saying that he who is chief should become the servant of the others. That's a pretty clear designation of Peter right after defining what the chief should be like and how you would know the chief among them.
There is no contradiction at all unless you take part of the verses out of context, quote them, and ignore the rest.
Even if it agreed that Peter had some sort of leadership role with regards to the other disciples, the Bible doesn’t say that Peter had ultimate authority over the other disciples when it comes to theological matters.
The Bible also doesn’t say that once Peter passed onto to Heaven then another head apostle (pope) is to be appointed over all of the other apostles.
And I could have included previous verses proving He was talking to all of the apostles but I thought people could read the entire chapter for themselves without me taking up space. There is way more evidence in scripture to show that Peter was not the leader, pope, or any other top guy type designation.
You need to read the Bible for yourself and not just listen to some guy telling you what to believe. Luke tells us in Acts 15 that the Apostles all got together in Jerusalem after Paul and Barnabas had a disagreement to discuss the issue. James was the one who declared what the position would be on the issue.
Acts 15:12 Then all the multitude kept silence, and gave audience to Barnabas and Paul, declaring what miracles and wonders God had wrought among the Gentiles by them. 13 And after they had held their peace, James answered, saying, Men and brethren, hearken unto me: 14 Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for his name. 15 And to this agree the words of the prophets; as it is written, 16 After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up: 17 That the residue of men might seek after the Lord, and all the Gentiles, upon whom my name is called, saith the Lord, who doeth all these things. 18 Known unto God are all his works from the beginning of the world. 19 Wherefore my sentence is, that we trouble not them, which from among the Gentiles are turned to God:
Before you use the excuse that Peter wasn’t there you had better read the whole chapter, especially verse seven where it tells us that Peter was there and spoke to the group.
Also in Luke we see that the disciples themselves did not think that Peter was the designated leader or they would not have asked the question of Jesus they did.
"Now there arose a dispute among them, which of them was reputed to be the greatest. But he said to them, 'The kings of the Gentiles lord it over them, and they who exercise authority over them are called Benefactors. But not so with you. On the contrary, let him who is greatest among you become as the youngest, and him who is chief as the servant.'" (Luke 22:24-26)
If Jesus had designated Peter the leader He would have told them at that point but He clearly didn’t. The RCC uses Matthew 16:18 to try to justify the papacy yet 26 years later when Luke was written it was clear that Peter was not the leader.