Additionally, there's still a lot of Cold War associations propping up the "Israel GOOD, everyone else int he region BAD" meme.
The Soviets backed Israel's enemies in the region, mostly because we were backing Israel (even though the Soviets also backed Israel at times) and we were initially far less pro-Israel than Europe (Suez Crisis ring a bell?).
Europe backed Israel out of guilt. We came to back them out of geopolitical strategy. Guilt fades over time (especially when you realize you're making up for one atrocity by turning a blind eye to another).
Geopolitics change over time too, but it's become too deeply embedded in our politics. We no longer need Israel as a strategic beachhead in the region, and we don't need to worry about fighting "Communist influence" in the region. We do need to worry about Islamist influence in the region, but backing Israel is perhaps the single worst way to combat that.
The ironic part is that in the 1940s and 1950s, most of the Arab world LOVED the United States. After all, we had no history of colonialism in that part of the world so they felt they could trust us much more than the Brits or French or even the Soviets. Even in the 1970's, the PLO targeted Europe, not the U.S. They still hoped the Americans could be some kind of neutral arbitrator. It really wasn't until the 1980's, when Reagan made Israeli security a US national security goal that things really went to shit.
There is the rather large issue that Palestine doesn't trust US leaders at all because of how staunchly pro-Israel the US has been for the past 80 years.
Not so much. Eisenhower essentially backed Egypt in the Suez Crisis, up until the Soviets threatened to land troops in Sinai to keep the Israelis from massacring the Egyptian Army divisions trapped there. LBJ didn't trust Israel. Nixon didn't trust Israel. We really were neutral or at best cautiously pro-Israel up through the 1970's. Reagan was the one who made the choice to markedly ally ourselves to Israel. Prior to that, Republican foriegn policy was isolationist and avoided entangling alliances like Israel and Taiwan. And since it was the Great Gipper who did it, all subsequent Republicans have mostly accepted alliance with Israel as a tenet of faith.