Why was only Peter given the Keys?
...Are the keys of the kingdom of heaven given by the Lord to Peter only, and will no other of the blessed receive them? But if this promise, 'I will give unto thee the keys of the kingdom of heaven,' be common to others, how shall not all things previously spoken of, and the things which are subjoined as having been addressed to Peter, be common to them?
Origen...Its clear, you see, from many places in scripture that Peter can stand for, or represent, the Church; above all from that place where it says, To you will I hand over the keys of the kingdom of heaven. Whatever you bind on earth shall also be bound in heaven; and whatever you loose on earth shall be loosed in heaven (Mt. 16:19). Did Peter receive these keys, and Paul not receive them? Did Peter receive them, and John and James and the other apostles not receive them? Or are the keys not to be found in the Church, where sins are being forgiven every day? But because Peter symbolically stood for the Church, what was given to him alone was given to the whole Church. So Peter represented the Church; the Church is the body of Christ.
... One man receives them; you see, he explained himself what the keys of the kingdom mean: 'What you all bind on earth shall be bound in heaven; and what you all loose on earth shall be loosed in heaven' (Mt 18:18). If it was said to Peter alone, Peter alone did this; he passed away, and went away; so who binds, who looses? I make bold to say, we too have these keys. And what am I to say? That it is only we who bind, only we who loose? No, you also bind, you also loose. Anybody who's bound, you see, is barred from your society; and when he's barred from your society, he's bound by you; and when he's reconciled he's loosed by you, because you too plead with God for him.
Augustine
Cordially,
Keys are intended to OPEN something.
Peter was Gods man to OPEN the gospel to the Jews.
He opened that Door as he preached with power on Pentecost. Once the door was open the keys were no longer needed.
The keys have been returned to Christ.
Rev 1:18 I [am] he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
Whose hands had sown the Divine seed in the ground, that is Rome, we shall never know Conjectures built upon foundations too insecure to be sanctioned history ,takes the Apostle Peter to Rome during the first reign of Claudius AD 42...About the time that that St. Paul gained his liberty, St Peter came to Rome.He had perhaps been there before. But it can not be proved. We have no information whatever as to Peters apostolic work in Rome Early History of the Church Abbe Duchesne ( Roman Catholic Historian)
The keys to the kingdom of heaven are the gospel of our Lord and Saviour Jesus Christ. Peter was given them to preach to the Jews. The rest of the apostles and disciples, including us today, have the keys. They aren't locked up in the Vatican.
Best, OP