Pope Urban I, was actually born ‘Urbanus’ and became Pope in the year 222. The name ‘Urban’ is very simply the Anglicised version of his name.
It only became common for an elected Pope to take on a new name in the 1300’s, so there was a lengthy period of over 1000 years where Popes are believed to have simply used their birth names. The first known Pope to change his name was John II in 533, who was born Mercurious. He considered that using his birth name could cause issues because his name had Pagan roots (in the Roman god Mercury). By changing his name, he appears to have set a precedent for later popes, although it didn’t become commonplace until much later on. There is also a not-so-subtle nod to the Bible - Saint Peter was given that name by Jesus, his actual name was Simeon!
So, why so many Urbans? Well, it is believed that a Pope selects their Papal name carefully in order to signal to the community what policies they will adopt and the direction in which they will seek to take the church. Selecting the name of a previous Pope signals that they may emulate one of the previous Popes using that name. Not a lot is known about Urban I, but the little we do know indicates that he valued generosity toward the poor.
You may also be interested to learn that Urban is far from the most popular Papal name. John is the most popular, followed by Gregory and Benedict. Also, no accepted Pope (yes, there have been disputes as to who is the Pope over the centuries) has used the name Peter because the Catholic Church considers Peter to be both a Saint and the first Pope, so the name appears to be “off limits” out of reverence to him, although a number of Popes were actually born Peter! It’s obviously not a problem because tradition allows them to change it!