My daughter learned to jump because she learned she could walk over and hit the spacebar and see immediate feedback on almost every game we played, but at the time I was playing through one of the Tomb Raider games so I'd relatively frequently walk away with the game unpaused. Then she connected the dots of what she saw on screen and tried repeating the motions she saw Laura doing and did her first jumps mimicking what she saw on screen.
So in summary, Laura Croft taught my daughter how to jump.