Why are the Palestinians Israel's problem?

Look how the Arab world treats millions of Palestinian Arab refugees in their countries. Israel is smaller than Rhode Island, but the world expects it (under right of return) to take in all the Palestinian refugees, the majority of whom weren’t even alive in 1948.

The only ethnic cleansing of Palestianian Arabs has been done by Arab nations that to this day, hold them in horrid refugee camps, using them as political pawns. Jordan (which was designated by the UN in ’48 to be the Palestinian state) has killed or driven out many thousands of  these refugees (who rightfully should be living in Jordan, the real Palestine). But the subjugation continues. And no one says a word.