Weirdly, in the 15th century, pretty much everybody knew the world was round.
Hell, since the Greeks!
Walter Baker wrote about it in the 13th century even.QI -series 3, episode 1 - The world was never flat
Also, in the 19th century, the Church was a big supporter of Darwin and his Theory of Evolution.
Since the publication of Charles Darwin's On the Origin of Species in 1859, the attitude of the Catholic Church on the theory of evolution has slowly been refined. Early contributions to the development of evolutionary theory were made by Catholic scientists such as Jean-Baptiste Lamarck and the Augustinian monk Gregor Mendel. For nearly a century, the papacy offered no authoritative pronouncement on Darwin's theories. In the 1950 encyclical Humani generis, Pope Pius XII confirmed that there is no intrinsic conflict between Christianity and the theory of evolution, provided that Christians believe that the individual soul is a direct creation by God and not the product of purely material forces. Today, the Church supports theistic evolution(ism), also known as evolutionary creation, although Catholics are free not to believe in any part of evolutionary theory.
It the insane Flat-Earthers and ignorant right wing nutters that are the problem, as always.
I could go on about gravity as well if you like, but yeah, generally, with the advent of mass communication, radios, then television, then computers, it is easier to see the stupid people, so we assume that everyone is stupid.
And sadly, stupidity gains followers more quickly than informed intelligence.