Babylon is an entity that is not just a first century entity (Jerusalem) as you believe, but is a global entity that is still around and not destroyed until Christ returns, which He has not yet done
Mystery Babylon was NOT titled a "global entity", as you are proposing. That would add to Revelation's symbolism which we are given. The interpreting angel told John that Mystery Babylon was
a single "that great city" who was charged with the blood-guilt of killing the prophets and apostles and the saints slain on the earth (Rev. 18:24). This is exactly the charge Christ brought against Old Jerusalem in Matthew 23:37. Christ said that Old Jerusalem's religious leadership was going to "fill ye up the measure of your fathers" (Matt. 23:31-32) by killing the early church prophets, wise men, and scribes that He was going to send. These disciples would be scourged
in the synagogues, imprisoned, and persecuted by Old Jerusalem's religious leadership - and the Apostles and disciples
were treated this way, as the book of Acts records. (No believers today are being scourged in a synagogue, or will be either.)
•Mystery Babylon is described in Rev. 17:9 as a city that sat on seven hills (Old Jerusalem's Mount of Olives, Mount Scopus, Mount Zion, Mount of Evil Counsel, etc.)
•Where Mystery Babylon sits upon the waters in Rev. 17:1,15 represented the fact that the city Old Jerusalem was a central location for the trade routes which crisscrossed through this region. Those waters also represent the fact that pilgrims from multiple nationalities came to worship at Old Jerusalem's temple, as evidenced by the list of nationalities present on Pentecost day in Acts 2:7-ll.
•Mystery Babylon who was then
"reigning over the kings of the earth" in John's own days was a description of
Rome-governed Old Jerusalem who had the HIGH PRIEST "kings of the earth" under its control at the time. "We have no king but Caesar" was the Jewish religious leadership's admission of this. The term "kings of the earth" is
not used in Scripture to describe regular monarchs over the globe's countries. "
Kings of the earth" means high priests of the land of Israel in Scripture's terminology (such as Matt. 17:25, Psalms 2:2).
•Mystery Babylon was going to become a "prison
(phulake) for every unclean spirit", and "a habitation of devils" (Rev. 18:2). This is exactly what Christ predicted for His own people's first-century "wicked generation" in its "last state" in Matt. 12:45-46. All those unclean spirits which He had cast out of Israel's citizens during Christ's earthly ministry would return in seven-fold numbers more wicked than before, making Israel's "last state" worse that its "first state" when Christ had been among them. The entire Satanic realm of evil creatures were imprisoned within Old Jerusalem until its AD 70 destruction.
Mystery Babylon / Old Jerusalem was judged and destroyed back in AD 70, with not one stone left upon another inside the walls of the city. That temple and the priesthood which operated in it were likewise thrown down, never to be found any more at all, just as the angel described in Rev. 18:21.
The unshaken New Jerusalem since AD 70 has been left in place as the current reality in which we dwell. Old Jerusalem was shaken and removed from existence back then, never to re-emerge with any spiritual significance in God's eyes. We are not waiting for this to happen. It is done.