As Rabbi Rotenberg (zt"l) said, history consists entirely of old facts and there is no room for "innovation" of any kind.
The problem with old facts is that even these may not be reliable. I am working on a historical novel taking place in the US in 1799, and even using several detailed sources referring to the events described, am having the following difficulties. Don’t know if the historical villains are who they say they are since there is a distinct difference in ages quoted, don’t know if their purported consorts are the same in the two most detailed accounts. So I have to make a decision as to which version to emphasize. Two thousand years and more ago, you had to rely on oral tradition for a lot of information that might be several hundred years old, then you had to make a decision on which tradition to chose, then you had a Roman emperor tell you to stop arguing and decide on one set of information for everyone, and then you had a political battle between the folks from Constantinople and Alexandria as to which facts would be picked with Constantinople winning. So perhaps there is objective evidence out there on which to base conclusions about whether the correct “facts” were the ones chosen.
Regarding the physical state of the Mediterranean, it appears that before the end of the Ice Age, that sea level was below the entrance to the Med from the Atlantic Ocean at Gibralter. As the sea level rose, water began to flow over this land and tear a channel which became larger and larger the higher the sea rose. There is also evidence that at a later time, the waters of the Med were able to break a barrier and flow into the Black Sea. Here are some views of the history of the Med and sea levels. I was not able to find some of the best ones I have seen earlier, but even these will give you some idea. For example, red areas show that the Adriatic Sea was land, and England was connected to Europe. Will try to find better maps when I return from a meeting.