The early middle ages weren't exactly a nice time to be living, that can't really be said of late antiquity either except for the elite. For the serfs it would hardly make any difference.
Because of the splintered makeup of medieval Europe, its history is way more dynamic. Events like the invention of gunpowder and the discovery of America (wich happened outside of the middle ages proper, but the causes can be found in it) can easily be explained from this perspective. On the other hand, empires with political unity that span most of the known world from their perspective like Rome or China, don't get much done- the history of both is one of remarkably little technological progress.
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