The Arabs revolted under British rule in a war that began in 1936. Who owned the land during that revolt? The British controlled the land but there were Jews and Arabs living on the land at the time. During WW2 the Arabs joined league with Hitler to annihilate the Jews in the Middle East, especially those Jews living on lands controlled by the British that now land belong to Israel.
The 1948 war was not a war started by Israel in effort to steal land belonging to Palestinians, but was a war started by Palestinians seeking to prevent Jews from taking possession of British properties given them as part of the British two-state solution to the area as they withdrew from the area.