> The numbers are largely unknown for border crossings.
Actually, we do have a very good idea. The demographics of Palestine were studied at the time (e.g., by the Anglo-American Committee of Inquiry), and are well understood. Arab population growth in Palestine was almost entirely due to simple births minus deaths, and was similar to population growth in other Arab countries of the time.
> But the point is that it's a gross oversimplification to say that Palestinians are native to Palestine (even those born outside?) while Jews are not.
Which Jews? There were Jews who were native to Palestine. They made up a few percent of the population of the region. But the overwhelming majority of the people who founded Israel were recent immigrants. The first Israeli prime minister, David Ben Gurion, was from Płońsk, Poland. The first president of Israel, Chaim Weizmann was from Belarus. Golda Meir was from Odessa and grew up in Milwaukee. You can go down the list. They're almost all like that. Heck, the founder of modern Zionism, Theodor Herzl, was from Budapest, and barely ever set foot in Palestine (only once, I think).
> The intentional naming collision encourages this oversimplification.
The reason for the naming collision is simple: the Palestinians are the people who lived in Palestine before the Zionists came in, took over most of it and established Israel.
> Many of them simply had no choice, having been driven out of other MENA states.
No, that happened in the years after the founding of Israel, as a consequence of it. It turns out that kicking out hundreds of thousands of Arabs from their homes and loudly proclaiming that you're doing so in the name of the Jewish people is a really effective way of stoking antisemitism in Arab countries.
> I don't think that it's wrong to legally immigrate, regardless of any statehood aspirations, or that such immigrants are less deserving of any rights than other residents.
If you read the scenario I sketched out above and think it's the same as everyday immigration and is okay, I don't know what to tell you. It's like calling the European settlers who drove out Native Americans "immigrants."