You could hardly call the Wright brothers' engine a "practical means" of propulsion. It had no lubrication system beyond the application of an oil can before start.
That Caproni, "useless" or not by virtue of 20/20 hindsight must have taught their engineers an awful lot despite not being a complete jet engine. Just because Von Ohain and later Whittle beat them to it doesn't make it "utterly useless", does it?