Agreed that his ethnicity is a silly topic to be discussed, but calling Christopher Columbus a "slightly" relevant guy definitely feels like a stretch.
He was a small gear in a long chain of events. If not Columbus, someone else would likely have found the New World. It was the age of (Europeans) Discovery after all, where many people were sailing the world and finding new routes and lands.
Sure. This is just Great Man theory [1] in action. It's a bit absurd, once you know about it you see it everywhere.
It's especially distasteful when it's about people who 'discovered' places, because the next step was usually the subjugation or genocide of the people already living in the discovered place. But we still celebrate the explorers as heroes.