You really misunderstood my point (apologies if I was unclear). Of course they held to a young earth b/c that’s what the Bible seemed to teach. But I’m focusing on the ism in creationism, which gets into correlating a young earth with modern scientific ideas, whether or not they corresponded with mainstream scientific notions. By definition, this could not be the traditional position of the church b/c it didn’t have modern scientific data.
As far as I know, there was no premodern quasi-scientific way of determining age (someone correct me if I’m wrong). What did operate from is a Ptolemaic system about the shape and relative movement of things (which is why geocentrism was the “scientific” consensus, which could be squared with biblical interpretation).
Seriously?
That’s more complicated. Most cultures organized into a 7-day week, and we don’t know when/how it began.
EDIT: @RonSewell below describes my main point better than I did.