The Arab world never cared about the Palestinians.
I disagree. Many Arab states and ruling families were newly created, and there used to exist a pretty strong pan-Arab feeling of brotherhood. They had been governed by larger entities for centuries under first the Ottoman then the British and French Empires. So national identity was weak and pan-Arab identity was strong. Think Nasser. Most Arabs took pride in becoming independent and throwing off the yoke of colonialism, except there were the Palestinians still dispossessed of their land and caught up in European dominance. Then there was also the rise of Muslim identity, which abhorred Zionism and its Christian supporters.
No matter what the ruling elites thought of the Palestinians, the Arab street did care about their plight, seeing in it a mirror of their own previous struggles, and feeling a significant Arab brotherhood. More recently, nationalism and domestic policies, and the ability to affect domestic politics has pushed any concern for the Palestinians way into the background.
There also has been a significant parallel shift, with leaders of Arab countries willing to work with Israel, but their people still strongly against such cooperation. Israel's only real enemy these days is Iran and tiny Lebanon. You can add Hamas in Gaza and Assad in Syria, but they are so weakened and in disarray as to pose no real threat.
Overall, things have changed dramatically. The center of the Arab world has shifted from corrupt sclerotic Egypt to the Arabian peninsula where wealthy Saudi Arabia has staked its claim, while the UAE and Qatar play outsized roles. Turkey, formerly a pariah and coup-prone, has tried to muscle into a leadership position. While Iran has also sought to fill the vacuum, limited by being Shiite, but helped by the US overthrowing the Sunnis in Iraq.