What popular old-school video game character was originally known as Jumpman?

The answer is: Mario. Mario made his first appearance in the 1981 Nintendo arcade game Donkey Kong, but he wasn’t known as Mario during production — he didn’t even have a name. His character was simply called “Jumpman” because he had to jump over barrels being thrown by Donkey Kong. He was also sometimes referred to as “Mr. Video.” If that’s not shocking enough, Mario also had a different profession back then: He was originally a carpenter, not a plumber. Source