The Wright Brothers DID Invent the Airplane

Check out Gregs Airplanes and Automobiles for really well researched aeronautic docs. He made one specifically about the Wrights ▶ this video

Basically, understanding airfoils. Back in the 1840s they put miniature steam engines in model planes and got them to fly. There were powered ground-effect planes in the 1800s that had more powerful engines than the Wright Flyer, but the Wrights were the first people to invent the wind tunnel, so they had a better understanding of lift-to-drag and control surface issues. They adapted the flow-pattern analysis tanks used by ship designers. As mcarmichael said ▶ this video

Control was an almost completely unaddressed issue before the Wrights took it up, even though it is also crucial to useful glider development. This video has a nice delineation of the collection of breakthroughs needed: ▶ this video

Not as narrow as many want to believe. The Wright brothers were the only ones doing actual engineering on the subject. They were 5 years ahead of everybody else and remember that being second is much much easier than being first, for one somebody else is the one making all the mistakes. ▶ this video