yeah that is possible, I think OP maybe is not truthful and was playing a modded hot-seat game though where they were playing as melborne. I mean someone would have had to conquer melbourne within the first 20 turns, then ramp up production and growth to get so many of those good early game wonders. It just seems like it wouldn't be something the AI would do. Also, it is something that just doesn't line up and combined with the fact that the post is already hard to believe (a city state conquering 120+ cities) I have my doubts that the game played out the way OP said it did.
I'm just going to be a skeptic and say he doctored this by doing a hot-seat game that was modded or something where he could play as a city state OR made a map that was already like this in the editor (hence the existence of the wonders). Also, beyond missionaries and prophets that are captured, I'm fairly certain city states don't produce great people (you can see great engineer, admiral, general, and scientist in image 2; great merchant in image 5 and great artist in image 5). These units are not capturable by military units. Other evidence of OP lying is the existence of the caravan in image 5, city states definitely can not build their own trade routes!
I don't care he doctored the game, and this is pretty sweet, but he clearly isn't telling the whole story.