In my opinion you are committing a logical fallacy here. Palestinians might be a new "construct" (the word) as you claim but that does not erase the historical, genetic and ancestral ties of the people that are nowadays called Palestinians to the region that their forefathers have inhabited for a very long time or since time immortal for some (ask a Negev Bedouin for instance who knows the Negev better than his own pocket and whose entire lineage is traceable to Negev) if he is not native?
Palestinians had states that ruled that land. Rashidun, Umayyad, Abbasid, Fatimid etc. Prior to that they had the Nabateans, Edomites and others.
There are no more Nabateans today (despite them being one of the greatest civilizations in history and the founders of numerous World UNESCO Heritage sites like Petra in Jordan, Mada'in Saleh in KSA, Bosra in Syria, Avdat in Israel) etc. to name a few, as in no people calling themselves Nabateans, but we all know (including us Arabs) that they are one of our many ancestors. We know that they originated from Hijaz and that they lived in Sinai, Levant and Northern Arabia. We have their architectural legacy as a proof. We have Greek and Roman records etc. There are no records of any genocide on Nabateans. So it is fair to say that the average Hijazi can claim kinship to Nabateans at least partially. After all no human or people are pure or have never mixed with anyone else but themselves for millennia, less so when you have the oldest recorded history in the world and live in one of the centers of the ancient world.
This is not the North Sentinel Island.
https://en.wikipedia.org/wiki/Nabataeans
Yet using your logic, it does not matter because it is all about the name.
So if one day Tabuk region breaks away from KSA and calls itself Arabia and its citizens Arabians, will they have a bigger claim on Arabia than other citizens of the Arabian Peninsula who live in countries that are not called Arabia? Of course not.
I disagree and so do most historians and neutral people from what I have seen. I have discussed this topic with geneticists, historians etc. despite my young age. I used to write long letters to random professors that I found on the internet in order to ask them such questions when I was a teenager because I wanted to know the truth. Later on I became very interested in genetics and became quite an "expert". Of course this is all a hobby among many hobbies for me. Yet I got a whole new perspective on history that many people sadly lack. I can now separate bullshit from the real deal.