When Columbus set sail most europeans believed the world was flat and that his ships would fall off?

Answer 1

False. Scientists and navigators have known since antiquity that the Earth is round; the Greeks actually had calculated the size of the Earth to within about 10% of it's actual size.

The uneducated masses, the farmers and landlubbers who had never been to sea; those people may have believed that the Earth was flat, because when you're a farmer or a shepherd, the Earth does appear to be flat. But every sailor knew that the Earth was round.

When Columbus set sail, his biggest mistake was that he believed that the Earth was only about 2/3 of the size it is; he also thought that Asia was larger than it actually is, so when his sailors hit land, he was pretty sure that he had reached Asia.

One final point; when maps are art rather than science, it makes perfect sense to draw mythical and imaginary beasts in those points beyond what was known. That's where the dragons and sea serpents came from.