I feel like the Dark Ages were innovative and productive culturally if you look at the culture of the time being dictated by religion. I think of it as the American culture of WWII being focused on patriotism, almost everyone was on board and patriotism was the culture.
The north spire of Notre Dame was rebuilt in 1506 and the intricacy of the new spire is a good example of the innovation during the late medieval period. The Bible moralisée during the time served to created a lot of innovative illustrations for the period and in my opinion display huge cultural advancement.