The word "Pope" is from the Greek orthdox tradition which means "Father" The word is used as Title of an ancient office originally held by Saint Peter.
Under Saint Pauls revision of the Church from a Commune in Jerusalem, to an Episcopal heirachy, the original apostles became missionaries and settled in different lands. apart from Saint Paul who never got chance to settle down because he got executed whilst determined to convert the Senate of the Roman Empire
Each of the Apostles became Bishops of The Early Church, which happened for three hundred years between Pentecost, and Emporar Constentine. During that time a Church was founded in Rome, and Peter rulled his portion of the Church from there. He spoke mainly to the Jewish converts, whilst Paul and all the other Apostles spoke to the Heathern Converts.
After Saint Peter was executed, the Bishop of Rome office continued for Three hundred years until Emporar Constentine. This Emporar wanted to keep his Empire together by uniformity of belief. For hundreds of years the Romans had accepted any and all religions into their empire...and now there was chaos.
So Constentine decided to become a Christian, for political reasons
and he established the closest Bishop to be THE Bishop. That, obviously, was the one in his own city. The Bishop of Rome. He Renamed the Office as "Pontifex Maximus" Which simply put means "High Priest" the SAME term was used for the pagen High Priests. (although in light of the Christian Pontifex Maximus, all others were given the boot, naturally) Even now, you will hear people use the word "Bishop" and "Pontif" interchangably.
The Office continued until the split in the Empire, between Byzantia and Rome. Byzantia was in the East, and had their own Emporars, who were also Popes, though not from an ancient office. The East used the term "pope" to mean "Father" as in Priest. Of course as the nations drifted apart, so did the two versions of Christondom...Rome in the West became a powerhouse, so strong she held political importance, and used her spirituality to influence the monarch of Europe.
Byzantia was wiped out by the Islamic Invasion that conqured Constantinople, home of the Byzantia Popes and Emporars, and Greece, and Russia, and North Africa....only Rome Survived...and largely coz the Islamists ran out of steam.
The Papacy began its demise when the British rebelled. You see, the Popes claimed that because Scripture tells us Saint Peter had special spiritual powers...so it must be that everyone who did the same job as Saint Peter must also have those powers...thus you dont want to piss that person off. With the growth of Science, the dismissal by King Henry, and the invention of a Christian Church WITHOUT ROME...the Catholic Church lost much of its spiritual significance, and all of its political significance outside of a tiny corner of the centre of Rome.
The Other Apostles also founded Offices...many, and most were distroyed during the Islamic invasion of the Orthodox Church and Byzantia....but there is a Primate of Jerusalem...he's supposed to be decended from some Apostle...there is The Patriarch of Antioch...he is supposed to be Thomas...or Andrew I cant remember which. There is a third related to the Coptic Church of northern Africa...and a fourth somewhere verging on India. But these are Orthodox...they have no influence, and no microphone...and no historical interest except that they are all in jobs once held by original apostles
It should be noted that Rome was very unkind to some of its Holy Orders...like the Jesuits and The Knights Templar...each time an institution became powerful enough to rival Rome...she squashed it. the Jesuits were lucky to survive...the Templars werent so lucky. The instituion surrounding the Pope is The Roman Curia...which is a law unto itself at times. Without a Pope it runs itself...with a Pope it is supposed to be subservient...but...its a political machine