and upon this Rock I will build my church, and the gates of the hell shall not prevail against it." The contrast is between Peter (the little stone) and Jesus The Rock of Ages. Also note the gates of hell prevailed against Peter when he denied His Savior, not once, not twice but three times. Let's go farther in the chapter to v.23 "Get thee behind me Satan; thou art an offense unto me, for thou savorest not the things that be of God, but those that be of men". The empowerment of Peter (and the other eleven)will come in Heaven when the binding and loosening takes place.
I commend you for looking beyond the contrived or forced interpretation to the context of Scripture. Because He is the Word (Logos) made flesh every word of Scripture is as important and precious as every crumb of the Eucharist.
Following the feeding of the 5,000 near Capernaum Jesus took Peter and along with the other Apostles and Disciples up to Caesarea Philippi to reveal his papacy to him. The selection of the location is far from a coincidence. Caesarea Philippi is a 25 mile, two day hike from Capernaum through some pretty rough country.
At the site of the revelation is a massive exposed rock cliff. Atop the rock stood the city of Caesarea Philippi. It was a very important location militarily, and had been a place of temples and worship dating back thousands of years before the first century. At the base of the cliff is a massive grotto that at the time was a natural cistern that the Greeks and their predecessors believed was an a gate to the underworld. Physically, that rock stood between an city of temples and the gates of hell.
Jesus then told Peter that he was a smaller rock, and that upon it, like the larger rock upon which was built the city before them, He would build His Church and that it would stand forever against the gates of hell. A side note is that all of this arguing about the relevance of Petros versus Petra is foolish in the context of that location. Jesus often used wordplay and humor to convey His message.