Yeah, the whole Flat Earth stuff is a relative modern re-occurrence.

We've had concrete evidence of a globe Earth and a pretty accurate measurement of the circumference since the 3rd century BC (Erastothenes). ¹
Heliocentrism was theorized by the Ancient Greeks, but we've only had concrete evidence/math since the 16th century (Copernicus). ²

Then in the 19th century, you had the writer Washington Irving who wrote a romanticized biography of Columbus and claimed that folks in the Middle Ages believed the Earth to be flat, which was just not true. ³

And then there was Samuel Rowbotham, another writer who just made up a whole load of bullshit and kind of brought the conspiracy theories underway. ⁴

¹: https://en.wikipedia.org/wiki/Flat_Earth
²: https://en.wikipedia.org/wiki/Heliocentrism
³: https://en.wikipedia.org/wiki/Myth_of_the_flat_Earth#Irving's_biography_of_Columbus
⁴: https://en.wikipedia.org/wiki/Samuel_Rowbotham

I mean, they kinda do. All the flat earth models I've seen have a tiny sun going around in a circle above the disc.

well, to be fair, we can see the same amount of stuff in every direction without an edge. and at the rate of expansion, we could never reach the 'edge' we can currently see. so we kinda are at the centre of the universe

I've never come across anyone who believed in heliocentrism, ever. Is that a thing?