> Their contribution except for first flight is very marginal
Absolutely untrue. The Wright Brothers brought their breakthrough into the market in a big way, becoming a (not the only) major manufacturer of commercially available, working, reliable aircraft.
True, they fought patent battles, and in the end their reliance on wing warping (covered well by their patents) held them back when it became clear that ailerons were the way foreward - but they certainly were more than just experimental researchers. They truly did usher in the age of practical, heavier-than-air flight.