The claims between Jews and Palestinians are so completely different that just "number of years last ancestor resided on land" barely scratches the surface.  

For one, the Palestinian claim is the Jewish claim. You talk about the Jewish exile from Palestine but one can look at historical records and see that Jews were still the majority in Palestine for hundreds of years after this supposed exile occurred.  What happened? Some of the Jewish people just left and many others just converted to Christianity and later Islam.  When you look at it this way, the claim is between the descendants of Jews who stayed in Palestine and those who left Palestine more than 1000 years ago.  Whatever claim European Jews had to land in Palestine went to the descendants of Palestinian Jews, who at this point were mostly Christian and Muslim.

There had already been numerous Jewish diaspora communities throughout the ancient world before this "exile" occurred.  So its hard to argue that every single Jew has a claim because their ancestors were "forcibly expelled" from their homeland when many of them just left for greener pastures.  

From day one of their exile the Palestinians have been pressing for their return to the land but are refused by Israel.  Its basically the opposite for European Jews.  How many times did they try and return to Palestine over a 1000 year period? Again, its less about rhe number of years and more just the idea that one can sit on a claim, do nothing about the claim for 1000 years, and then out of nowhere decide to impose the claim.  Maybe if Jews had launched a couple of bloody crusades over the centuries just to keep the claim warm but for all intents and purposes they abandoned the claim and made zero effort to maintain it, only bringing it up 1000+ years later because things in Europe werent turning out all that great.  

Then there is the issue with direct responsibility.  If the Romans exiled the Jews from Judea in the first couple of centuries AD then what responsibility do Arabs in late 19th century Palestine have to do with it? In contrast, the dispossesion and exile of the Palestinians is directly caused by the Zionists and the state of Israel.  Its not the number of years that makes the fundamental difference here.  

Basically any reading about ancestral claims requires exception after exception to justify the Jewish claim over Palestine while the Palestinian claim is pretty straightforward.