The conclusion I always come to is we're lucky to be born where we are because, through most of history, it was no uncommon for a man to die before his 30's, and even 50 years ago a man dieing at 50 wasn't a shock.
Now, average life expectancy is up in the 80's, and will probably be much higher by the time I'm an old man. It's amazing how fast we've grown in the last 100 years.
I think the fall of the Roman Empire saw us fall back hundreds, maybe thousands, of years in our progress.
In some respects, perhaps. But the empires that absorbed territory also absorbed practices, and many of the things one would associate with progress were actually maintained for centuries beyond whatever point in time you ascribe the actual "fall" of the empire to (a mate of mine did their dissertation on the topic). I mean the reason we have so many of their writings is because conquering factions decided to preserve them (and the writings we have lost have mainly been due to lost locations etc rather than discrimination of text). Furthermore, victories against the Romans were not orchestrated by pastoral nomads, as a channel 4 documentary would have you believe, but by educated leaders thoroughly versed in Roman tactics (some of them were even taught by the Romans themselves) and disciplined soldiers. In practically every way imaginable Roman life and lessons have permeated the vast ages between us, from engineering to medicine. My lecturer at Uni, no joke, was asked by Obama to go over to America to help with their financial crisis because he's a foremost expert on the roman economy!
In my opinion, one of the most powerful lessons the Romans (and many civilizations before them) have taught us, is the importance of strong leadership to effectively equate themselves with the most powerful entity (ie God). It instills longevity and projects success, as well as forcing fear upon populations to remain loyal to the supreme power. This is still happening in many of the powerhouses of world politics like China/USA, and will no doubt continue to happen despite the "rationality" people will always claim they have.