the fact that the Earth spins was discovered only a few centuries ago

The earth's rotation may have only been proven recently, but it's been suspected long before. Heraclides Ponticus argued that the earth rotation on a north-south axis once every day, and Plutarch tells us that Aristarchus of Samos believed the same thing.

In any case it's not at all necessary to know the rotational axis of the earth to know about north and south. Unless you're firing off rockets or something that needs a ridiculous amount of precision north and south can be determined perfectly well by sun and stars

You don't need to know the earth spins to watch the sun traverse the sky every day and the moon every night, and to deduce that there's a general path it follows every time which can provide permanent orientation. The place where the sun rises is one orientation; the place where it sets is another. Draw a perpendicular line through this path and you've got two other orientations, and a million degrees in between each. Ancient and medieval people saw the horizon as a circle around them; they divided that circle into four quadrants; "North", "South", "East" and "West" came out what were thought to be the four principle winds based on the sun's path. These four quadrants were then subdivided, in the case of the Greeks, in to 12 sub-winds. Of course they didn't call it "east" or "west"; medieval Europeans in the western Mediterranean and Italy called the east "Levante", meaning "rising" of the sun, and west was "ponente", meaning "setting". For the Italians, north was "tramontane", which means "over the mountains", and south was "ostro", which meant...well..."south".