There are plenty of inventions that got developed over time, like photocopiers and steam engines, or had varied designs, like the steamboat. So, it can be hard to pinpoint the exact moment when these devices were invented , and by which inventor. For the inventor of the telephone, for example, you could have quite a good debate about the respective merits of Alexander Graham Bell , Elisha Gray and Antonio Meucci .

However, the airplane is not one of these. Yes, there were quite a number of bright minds working on the problem in the 19th c., and the Wrights took advantage of that work. Greatly owing to the help of Octave Chanute, they could read about Lilienthal's work, and about Eiffel's wind tunnel. And the Wrights did delay public demonstrations after their 1903 flights at Kitty Hawk, which led to some grumbling by the press and public, and it did raise some doubts . But when they did begin to fly publicly, in 1909, there was absolutely no question as to what they'd done. There had been plenty of other aviators who'd done managed short hops or even rather long glides in various kinds of planes before hitting the ground, as most relied on the dihedral of the aircrafts' wings to provide some stability. With their innovation of warpable wings, the Wrights achieved controlled flight. If there were no storms or high winds, the Wright flyer could take off and do figure 8's over the heads of awed spectators at the speed of around 40 knots until there was a need to land to add gasoline or fix the engine. The Wrights created the first airplane that could go up, stay there, and come down when desired. That, really, was the first airplane.

The Record Flights of Orville and Wilbur Wright. (1909). Scientific American, 101(16), 274. https://doi.org/10.1038/scientificamerican10161909-274c