Historically, there are a number of reasons civilization and advances flourished in Greece. Firstly, Greece, as we know it today, didn't exist in the heyday of that culture two or three thousand years ago. Having said that, there are some simple to understand (good for me) reasons for the advances seen. One is the old maxim of location, location, location. The early city States or poli were located along trade routes and benefited from interaction with many other peoples. (One of the major city States (Cyrene) that contributed greatly to medical advances was actually in northen Africa). Secondly, bad farming... the soil in the southern Mediteranean is thin and rocky, supporting only a few people per hectare. Hence, the Greeks, early on, turned to the sea and became excellent sailors, at least in the Mediteranean basin. (By the way, the rocky, mountainous region also made it difficult for others to invade or attack the city states). Thirdly, their wide travels exposed them to the Phoenicians from whom they derived an alphabet and written language. The language development is one of the major keys... it became the lingua franca of the entire civilized world. All of these attributes, in my opinion, contributed to the advances demonstrated by history and archaeology.
It really wasn't an internally developed superiority but an inate ability to take advantage of the cultures with which they came into contact and incorporate them within their own... my opinions only...
Contd.