The facts that the Earth is a sphere and that it is somewhat more than 24,000 mi in circumference have been known since the early Greeks experimented and calculated before the birth of Christ.
The knowledge was never lost.
It amazes me that people still inaccurately claim the Columbus pushed against the idea that the Earth was flat. He did no such thing.
The only bit of scientific knowledge that he pushed against was the earth’s known circumference, which as you point out, he was wrong about.
It’s really unfortunate that such inaccurate ideas about him fill the popular imagination.
It’s more unfortunate that people refuse to face up to the fact that he was a brutal murderer.