Uh, except for the five centuries from the 1400s until Serbia invaded and conquered it in 1912 as part of the First Balkan War. I'm sure there's a library near you. Ask someone where it is. They usually have nice ladies there who will help you look it up.
The liberary would have told you that the Serbs were driven out of Kosovo at the end of the 17th century (1690) and that Patriarch Arseniye III (Charnoyevich) lead them to Voyvodina. The Serbs sided with Austrians in one of the three Austro-Turkish wars and were abandoned by the Austrians when the war fortune turned against them.
The Turks then decimated (literaly) Serbs across the area and caused them to leave en masse. The care taking of the Serbian Orthodoxy was taken over by the Montenegrin princes.
The Serbs were driven from their homeland. The Albaninas filled the vacuum. By your "logic" the Jews must not have the right to their state of Israel (historical reasons) either, if you believe that the Serbs "invaded" Kosovo after WWI (which was actually in 1913, after the First Balkan War -- I guess you didn't go to the library after all, did you?). If you think the Jews invaded Palestine without any cause than I would say the Serbs invaded Kosovo without any cause in 1913.
When the Serbs moved into that area in the 7th century, they didn't expel anyone or fight with anyone that I know of. It is therefore their homeland. Just as in the case of Israel, do you think that Arab numbers alone will determine if Israel has the right to exist or not? And one day there will be more Arabas in Israel then Jews.
What will the international community say then? Clearly, you and the rest of the international community are practicing double standards.
You favor integration in Bosnia at all cost, forcing people who don't want to live together to live together so that the Bosnian Muslims can have their country; yet when it comes to Kosovo, you favor disintegration. The only common denominator in both cases is the anti-Serb bias.
So, what else is new?
Kosovo is as Serbian as Aztlan is American.
Lemme guess, you want to run away on that question as well? Figures!