xkcd

The invention in question is called the "Instant Legolas" for reference

It's possible for someone to have made one as an experiment and it not being found, but it's also not very practical for war. Warbows needed to have 100-200lb draw weight to be particularly effective in battle. Trying to rapid-fire 5 shots from those bows would have been exhausting, and reloading the Instant Legolas was slow and would likely have reduced the total number of arrows you could fire throughout a battle. And having an extended period of time where you're unable to fire back when attacked is a major drawback. In modern firearm training, reloads are taught to minimize the amount of time the gun is incapable of firing, as a modern example.

Another big drawback to the Instant Legolas is that the ammunition needs to be shorter, reducing its overall weight thus further limiting its effectiveness against armor. While this does have the benefit of limiting your opponent's ability to collect your ammunition and fire it back against you, your side is then similarly limited unless your archers take the time to remove the Instant Legos from their bows in the middle of battle

The Instant Legolas would also have doubled or tripled the cost of bows and would have made them more difficult to store, which were significant problems with even extant equipment. There's plenty of example of soldiers abandoning or selling armor in favor of something less protective aimply because said equipment made marching too hard.