The Paliestains were not there before and does not get the land just for that. In fact, the jews were there in 530 BC even before the Paliestians were there.
https://en.wikipedia.org/wiki/HistoryoftheJewsandJudaismintheLandofIsrael
This is called fighting for what you want. We left and came back to show that we want to stay.
just because you had the land first does not mean you get to keep it. This is basically another preschool rule saying, "I was here first."
this is showing that they worked for the land and that they deserve it.
Just because they have always lived on the land does not mean they deserve it. Also, why does it matter that they leave in a big group?
The international community granted the Jewish people the land in 1948. United Nations including the U.S. gave land in Palestine to Israel. This is important because this shows that the community granted the Jewish people the land.