As an aside, nobody really believed the earth was flat: https://en.wikipedia.org/wiki/Myth_of_the_flat_Earth.
Your link only debates that during the Middle Ages people thought the earth was flat.
Those living in ancient Mesopotamia and Egypt believed we all lived on a flat disc or plane floating in the ocean.
As an aside, nobody really believed the earth was flat: https://en.wikipedia.org/wiki/Myth_of_the_flat_Earth.