To me, it’s: That ancient people thought the Earth was flat.
We have records from around 430BC where Greek philosophers spoke of the Earth being a sphere. In 240BC the Greek astronomer Eratosthenes calculated the circumference of the Earth and was only about 2% out.
The idea that historically people were somehow less, or more intelligent than people today.
Saying things like “ancient people knew over 300 plants and what they do” as if this is somehow amazing. Kids can name 300 Pokemon, and their movesets and how they relate to eachother. Your sportsfan cowoker can name their top 100 players and all their stats. This is not amazing, we just focus on other things nowadays.
Nor were ancient people stupid. Obviously they noticed things like certain events happening at fixed times of the year. They just didn’t have encyclopedias, but they did have centuries of passed-down knowledge.