While we are definitely back to the core question of "Great Man or inevitable progress of history" that characterizes the entirety of this discipline, I think that there are some key differences between what the Wright's were doing and everyone else. They were very open about how Lilenthal inspired them, but he was moving down a very different direction (trying to apply power through moving the wings, rather than propellers). Octave Chanute, the French-American engineer, was a critical node through which many of these early aerodynamic engineers communicated, serving the role that modern conferences and papers hold in sharing knowledge among all the people interested in a topic- including with the Wrights. But the Wrights still hold an important position in the birth of the airplane.

In particular, the Wrights found that their 1900 and 1901 gliders did not behave the way their math said they should, they spent 1902 recalculating from scratch all of the constant values that they had based their work on. They discovered that one number, Smeaton's Coefficient, a measure of the density of air, was wrong by about 40% (their value is correct to <1%, as best we can tell today). With the correct values, they built their 1902 glider, which behaved exactly as their math said it would, and laid the way for their 1903 Flyer. Again, even the 1903 Wright Flyer was pretty lame, but it took this entire lengthy process to get there, and the Wright's were the largely the ones pushing the envelope through this process. Other people would have, in the course of time, corrected Smeaton's coefficient, and then gone on to build the first airplane and the first one effective enough to be sold. But it is also true that the Wright's did all three of those achievements themselves, in the course of less than a decade.

Then, once their work was published and popularized, lots of people like Santos Dumont were inspired by them- he openly admitted that he built his first heavier-than-air flying machine based on pictures of a Wright plane. The French in particular quickly surpassed the work of the Wright's: Wright Co. was best in the world up to 1908 or so, and then got passed fast, mostly by the French, such that the US aircraft industry was far behind by the middle of World War One. Which is why English uses terms like fuselage and canard and monocoque for key parts of aeronautical engineering. The Wright Brothers were one link in a great chain connecting the first recorded stories of people flying- say, the legend of King Etana of Kish- to the modern commercial airliner. They weren't the only link, and they never claimed to be, but they were incredibly important ones. Were they irreplaceable in that chain? Well probably not. But in our actual history, their link was one of the biggest and most important.