If you are wondering who the first pope was, you will have to be more specific. There are a number of answers that could be given to that question.
If you ask Roman Catholics, no doubt they would say that Peter was the first pope. But if we go with that answer, we would have to put aside modern ideas of what a pope looks like. What Roman Catholics mean is that they believe that Peter was first bishop of Rome and that apostolic succession is derived from Peter.
Neither Peter nor any other leaders in Rome for the first few centuries would have called themselves pope. If they used any title, it was bishop of Rome (and I doubt Peter used that title).
Another potential answer could be Linus, who was the first bishop of Rome after Peter. According to tradition, Linus was the bishop from 67-76 AD. But we must accept that we are on shaky historical ground when it comes to Linus. We cannot be sure what is history and what is legend.
The word pope, which means papa, came to be used but not necessarily the way we use it today. It was generally used for any bishop, and not just the bishop of Rome.
It was during the time of Leo I, who was bishop of Rome 440-461 AD, that the term pope was used for that position. So in a way, Leo I was the first pope.
The fact is that the position of the pope really evolved quite a bit in the first five centuries, and continued to even after that. It is better that we not impose modern conceptions of the pope on the earliest bishops of Rome.
