Sorry to disillusion you with historical fact. But, yes, the majority of so-called Palestinians, by 1948, were immigrants, who gravitated to the area attracted by economic opportunities and an improved standard of living made possible by Zionist immigrants. Winston Churchill, who was present in Palestine, marveled at the industriousness of the Zionists in transforming the desolate desert and draining the malaria-diseased swamps, and, establishing an industrial base. At the same time, Churchill bemoaned the lackadaisical behavior of the Arab population. He remarked that if only Arabs lived in Palestine, for the following 1,000 years the land would remain barren and the economy unproductive.
Before 1880, the inception of Jewish immigration to Palestine, Arabs were leaving Palestine due to depressed economic conditions. Between 1880 and 1947, a period of heavy Jewish immigration, that trend had reversed, and, the Arab population had skyrocketed, in many areas by as much as 400%. New industries, such as the construction of a railroad, required new skills that Bedouin farmers and peasants could not offer, and, with the increased need for human resources, the British turned their backs on illegal immigration of Arabs, not checking visas. Those immigrants arrived from as far as northern Africa and as nearby as Syria and Egypt.