People have done merge sort, insertion sort, etc., by hand, for a very long time, probably centuries, and re-invented by many people. I would be very surprised

People have done merge sort, insertion sort, etc., by hand, for a very long time, probably centuries, and re-invented by many people. I would be very surprised if the steps had not been written down earlier. Algorithms done by hand, e.g. numerical methods, have been around for centuries too, so it's not that the concept was missing.