As one of the brazilian kind i have learned from childhood that Alberto santos dummont was the true inventor of the airplane but i couldn't get any good arguments from any american friends that were bases on true facts and not on blond patriotism, so,enlighten me please.
Are you asking why they were first or whether they actually were? The answer to why is more or less just that they were lucky; many people around the world were working on the problem of heavier-than-air flight and several were close to a breakthrough, including Dummont.
If you're asking whether they were really first then the debate becomes a question of exactly how you want to define terms like flight and airplane. Those who argue the title belongs to Dummont base this on criteria set by the Federation Aéronautique International, pointing out that the Wright flyer used a launch rail not a wheeled undercarriage, and was therefore not truly taking off by its own means.
See [this list of early short flights from FLIGHT magazine.] (http://www.flightglobal.com/pdfarchive/view/1959/1959%20-%200938.html) (Note the mild chauvinism displayed in calling the Ellehammer and Santos machines "impractical" - as if the Wrights' first flyer wasn't!)
There's a nice little article on cnet with some links to more detailed sources [here.] (http://news.cnet.com/8301-11386_3-57592900-76/were-the-wright-brothers-really-first-not-in-brazil/)
It's worth remembering what baby steps these first flights were. The Wright's first 1903 flight was only ~30 meters, Dummont's Oct 1906 flight was ~60 m -- a modern Boeing 747 airliner is ~70 m long from nose to tail!