First of all, let it be made clear that until 1948 nobody anywhere claimed to be a "Palestinian." If you had asked the ancestors of today's murderous Arab terrorists their nationality in those early days, they might have said "Arab," or perhaps "Syrian," or going back earlier, "citizen of the Ottoman (Turkish) Empire," but nobody in those days ever called himself a "Palestinian." The only people who even used the word "Palestine" to describe the territory were the British and — oddly — the Jews! (The name "Israel" had not yet been chosen, and the Jews were trying to decide on a name for it!)
There has never been an indigenous people in the area who called this territory "Palestine." The earliest people we know of in the region were the Canaanites, who lived there before Moses led the Jewish people out from Egypt. When the Jews settled there, it became "Judea." The name "Palestine" ("Palaestina" in Latin) was given to this territory by the Romans, when they defeated the Jews in battle and took over the land. (They gave the territory this name so they could claim it was not the Jews' land; the name came from the name of the Philistines, a people whose land was nearby. From the Wikipedia description of their territory, it would appear that a small portion of present-day Israel was inhabited by the Philistines; most of their territory was in today's Gaza Strip.) And from then until 1948, the territory was somebody's colony; the last two countries to control the territory before 1948 were the Turks and the British.
In 1918, the British took this territory away from the Turks, and first established a territory known as Palestine, which they governed under a mandate from the League of Nations. In August 1922, the Palestine mandate was split into two; one part was called "Transjordan," and is today the Kingdom of Jordan. So when someone speaks of "Palestine," it is not really clear whether they mean 1918-22 Palestine (which includes Jordan) or 1922-1948 Palestine (which does not).
In any case, "Palestine" in the 20th century simply was a term for the British mandated territory. Some Arabs in the area wanted it all incorporated in one pan-Arab state that included such current nations as Iraq and Saudi Arabia. Others wanted smaller nations; most considered that this territory would belong to a greater Syria that would include today's Lebanon and Iraq. But nobody considered Palestine (in either the 1918-1922 version or the 1922-1948 version) a nation in its own right.
In 1947, the United Nation passed a resolution dividing this 1922-1948 version of Palestine (which was only a third of the 1918-1922 version!) into two parts, which it might be noted were simply referred to as a "Jewish state" and an "Arab state." Nobody envisioned, even then, the Arab state as being called "Palestine" — that was still just a name for the British colony!
But in any case, the Arabs were not satisfied with just a piece of the Palestine mandate; they wanted it all. So they started a war with the Jews, and by the time the fighting ceased, the Jews ended up with slightly more territory than the UN had awarded them in 1947. This became the State of Israel.
For a number of years, the Arabs kept picking wars with Israel; the Jews kept winning those wars. And ultimately, the Arabs invented a new myth: the myth of a "Palestinian people" evicted from their land by the Israelis. There never was such a thing; there were Arabs, no different in any way from their neighbors in Jordan, Lebanon, and Syria, who thought of themselves as one group, and since the boundaries between these nations had been created by the British and French after World War I, the national identities of these people were not very strong. But by inventing this "Palestinian" nationality, they came up with a group that needed its own homeland, or so they proclaimed.
But who are these "Palestinians"? The people of a national group have something in common. The French speak French, and differ from the French-speaking Swiss and Belgians by having had allegiance to a government that has existed for centuries. The Swiss speak four different languages, but these people signed a constitutional document that bound them together in 1848, and so they have built themselves a nation (In fact, of course, groups of what now are Swiss had bound themselves into a nation in the 13th century, so they can be considered to have been building this nation for that long!) I challenge anyone to define a "Palestinian" for me -- neither language, nor religion, nor anything else defines a "Palestinian," except that it is an Arab who happened to have been governed by the British mandatory authority between 1922 and 1948 or a descendant of such a person. This hardly defines a nationality!
The Jews are united by religion. The Canadians are united by history; they have built a nation since 1867. But in no sense can the "Palestinians" be united as a people. Let us just avoid this word "Palestinian" — it is totally meaningless!