I didn't know about the 1947 Partition Plan. I looked it up on the wiki. Why did the Arabs reject it?
The Arabs of Palestine objected to sovereignty over roughly half the country being awarded to a bunch of recent immigrants. They particularly objected to it being awarded to non-Moslems, and
especially to it being awarded to
Jews, who would be ruling over hundreds of thousands of Moslem Arabs in their sector. (The 1947 division of Palestine created the largest possible Jewish zone that would have a Jewish majority.)
The Grand Mufti of Jerusalem, who was probably the most important Palestinian Arab leader, was a notorious anti-semite who spent World War II hanging out in Nazi Germany.
Middle Eastern Arabs were in general pro-Nazi during WW II, and always anti-semitic. (I know, I know - Arabs are technically semites.) Moslems in particular were intolerably offended by the notion of part of the
Dar ul-Islam becoming a state ruled by non-Moslems. Thus Egypt, Syria, Iraq, Trans-Jordan, and even Lebanon went to war in support of the Palestinian Arabs.
Also, fairly obviously, the territory left to Arab sovereignty isn't exactly a viable nation-state.