Who "Owns" Palestine?

Far too many people seem to think there's a clear answer to that question.

Arabs and Jews were both living in Palestine when the Ottoman Empire was dismantled after WW I. 

Both the Arabs and the Jews had been promised things for their support during WW I. The Arabs an independent state and the Jews a "national home." Leave it to the British to be vague in their terminology. The League of Nations agreed that the Jews were to have a "national home" in Palestine. The Jews have always interpreted "national home" to mean a Jewish state and the UN agreed with that interpretation after WW II.

Ultimately Saudi Arabia, Lebanon, Syria, Jordan and Iraq were created as independent states. The UN, in 1947, proposed a partition of Palestine into an Arab and a Jewish state with Jerusalem as an international city.

However, the partition plan was refused by the Arabs resulting in first a Palestinian Civil War and then a full scale war after Israel declared its existence in 1948.

The war was a disaster for the Palestinian Arabs. Israel ended up controlling about 77% of the land, including most of Jerusalem, Jordan controlled the West Bank and Egypt controlled Gaza. About 700,000 Palestinian Arabs were expelled or fled during the war.