If so, was the Umayyad Caliphate a non-literate society or is there evidence the Abbasids systemically destroyed older histories?
during the Abbasid dynasty
I'll start with addressing this first. It's better, in this context, to view the term Abbasid as an identifier of time rather than territory (the term can be used to identify a territory). A text written in the Abbasid era wasn't necessarily written in a territory under the jurisdiction of the Abbasid government, as the Abbasids when they first emerged only ruled part of the Muslim world (though a large one), and the size of their territory kept decreasing as time progressed.
If I'm understanding it correctly, your question is not concerned with epigraphic materials. So, I'll leave those aside. There were many pre-Abbasid scholars, for the sake of brevity, I'll limit myself to a few examples: