Mildly Interesting

Pretty much all of these examples were pretty often and commonly debunked by all of my teachers, parents, and adult mentors. But that's exactly why lists like this are garbage, both of our experiences are anecdotal. You just can't make blanket claims about things like this about entire generations.

Columbus was more a lie of omission than outright falsehood. That item on the list was probably closest to a universal truth taught across the US, as long as you ignore any school with an indigenous student body. But, most of our teaching about any historical figures in grade school is a near obscene over-simplification of the actual people and events.

widely spread myths

That's your problem. You can't seriously argue that these myths were being taught as fact in school because they weren't. They're all myths spread by common idiots through word of mouth. Common public misconception on the facts can and does happen very independently of actual education, as evidenced by antivaccers lately. The only things you could honestly add to a list like this would be some scientific theory that has been definitively disproven or amended. Maybe something like changing training about CPR would qualify also.

But those kinds of things are boring. It's much spicier to claim that people were taught that Columbus's contemporaries thought the world was flat even though that was just an over simplified story told to 5 year olds to explain why they got out of school on Columbus Day. Meanwhile anyone that didn't sleep through trigonometry should learn that Eratosthenes showed the world was round about 1700 years before Columbus. I would believe that there are some lazy educators out there that would teach such myths as fact, but to claim that it was at all universal is silly. The whole premise of "old generations dumb, look what they believed" is just so smug and offensive. I must be getting old.