And that for centuries countries all over the world, not just conspiracy theory obsessed Americans, know that the Earth is a sphere.
I'd just like to point out the obvious point that just because something is "known by people all over the world" doesn't make it true.
I'll give you an example...
For centuries all of Europe and the UK, not just racist Americans, "knew" that Africans were nothing but animals, they "knew" weren't human at all, and had no souls. They also "knew" that it was "God's Will" that they be taken into captivity and used as slaves.