An Australian, of course! The American media has drowned out every other viable claim to the first flier... just as they claim they won every war in the 20th century...
HARGRAVE, Lawrence : 1850 - 1915
November 12, 1894 - Lawrence Hargrave, the Australian inventor of the box kite, linked four of his kites together, added a sling seat, and flew 16 feet. By demonstrating to a sceptical public that it was possible to build a safe and stable flying machine, Hargrave opened the door to other inventors and pioneers.
The Hargrave-designed box kite, with its improved lift-to-drag ratio, was to provide the theoretical wing model that allowed the development of the first generation of European (and American) airplanes.
NOTE - Just to add a little more fuel to the fire, Hargarave also invented the rotary engine in 1889. He has never been credited with anything by the American media, simply because Hargrave refused to patent any design, and believed in collaraborative information sharing, and willingly disbursed all the findings of his experimentation. On that basis alone, he stands head and shoulders above those who would make claims based on financial benefit to themselves.
Lawrence Hargrave, Australian aviation pioneer, 1850-1915