The laborer no longer had to bend nearly to the ground with every shovelful to keep the dirt from falling off the shovel blade.
So simple, yet so impactful on lives and backs for the past couple centuries. Something that could have been invented 3,000 years ago...
I recall reading about the other important shovel innovation: reducing the size of the scoop; with smaller scoops, shovelers moved more earth overall, because they became less fatigued.