We really need an historian for this, it's just too much reading. The land of Israel has apparently existed for ~3000 years intill they lost it. I also read somewhere that jews has been hunted down and killed for over 5000 years (someone should fact-check this), so jews might view themself as victims. Politicians almost always respond to their voters.
Whether Israel existed before is pretty irrelevant to whether they have a claim for the land now. If that logic holds up, we would have to give pretty much all of America to native tribes, which I don't see happening.