The Jewish claims to the land are absolutely specious when you look at the available data. In the late 1800s the Jewish population of Palestine was negligible, about 2-3%, maybe a couple of thousand people. The current Jewish population of the country are not of the land, they are all colonial settlers who came from Europe and other areas with the intention of taking the land for themselves. Take the leader, Benjamin netenyahu for instance, his real family surname is Mileikowsky, they are Polish people, his dad made up the name Netenyahu to sound like a local.
The Palestinians however have deep ties to the region going back thousands of years sharing DNA with bronze and iron age Canaanites from the region.
The 1947 UN agreement wasn't a bad one for Israel, sure. They got over 55% of Palestine despite being colonial settlers fresh off the boat, free land for nothing. The Palestinian people had to give up the land of their ancestors that they had been continuously farming for thousands of years, wasn't such a good deal for them.
You are correct, Israel will not give the land back, that is not how the world works, might is right and all that. Israel is a tiny country both in land mass and population. 8 million or so Jews surrounded by 100s of millions of Arabs and other Muslim states. The only thing holding back the tide is Israel's relationship with the USA but this relationship is not set in stone. Look at the USA's history and how they have treated their allies in the past, the USA will drop Israel like they did the rest of it is in their own self interest. Now in the USA being tied to Israel is political poison, same in Europe. Foreign policy will eventually have to align with public opinion if officials want to stay in office. The world does not need an Israel to exist any more than it needs any other country.