The people living there before the UN created Israel were not "invaders."
1. The UN does not have the power to create States. So, right away I know your understanding of the conflict is limited and incorrect.
2. Current possession does not preclude previous invasion. Cases in point: Many Jewish people are currently in possession of Israel. Therefore they are not invaders. Many Europeans (and their descendants) are currently in possession of the United States. Therefore, they are not invaders.
You want to put it in context? Okay, suppose tomorrow the UN tells Alabama they're going to make it a Native American state ruled by Native Americans, and starts flying in millions of Native Americans. Then the Native Americans declare that only Native Americans can move there. Do the people of Alabama have a legitimate grievance?
Absolutely, unequivocally, NO! The people of Alabama have absolutely no grievance against the rights of the First Nations peoples to be present in the nation of their history and ancestry. Nor do they have the right to grieve against First Nations right to self-determination. I fully, absolutely support the rights of the First Nations peoples around the world.
But THANK YOU for acknowledging, truthfully, that the Jewish people are, in point of fact, equivalent to the First Nations peoples in this context and that the Arabs are the colonizers.
The solution for conflicts between indigenous peoples and people of long term residence is mutual co-operation and failing that, division of territory and mutual recognition.