This is a fallacious argument.They are not stuck with 4th or 7th Century beliefs.
Euclid is still relevant, and he wrote his works in 300BC!
Circles are round, triangles have three sides, rectangles four ... and those beliefs are really ancient ...

The Ancient Greeks proposed the earth was round in the 6th century BC. By the 4thBC, there was observational data. It was common idea in the Roman world and throughout the Middle Ages.
Today, there are flat-earthers ... so the age of data is no guarantee of anything.