UNSCOP, the United Nations Special Committee on Palestine, was created in May 1947. The Jews opted for separate states. The Arabs wanted none of this. There was an official boycott from the Arab side and in practice it was not as well represented as the Jewish side accordingly.

From the Jewish side, the committee met people of all factions. Ben Gurion had to make some concessions to the Ultra Orthodox delegates in order to get the on board with the idea of a Jewish State. In the other side, the Arab Higher Committee kept its hard line.

So UNSCOP suggested a middle ground: a federation of a Jewish State and an Arab State, where Jerusalem and Bethlehem remain in a neutral zone for now. There are generally more populated lands that are in the Arab part (indeed, a large part of the land given to the Jewish state is the Negev in the south, that was not densely populated).

Jews may have not considered that plan as optimal, but decided to stick with what they could get from the UN. Arabs rejected it.

And in the day following the vote in the UN, Arabs rejected it in actions: a civil war erupted. In that civil war, the Palestinian Arab side was not as well-prepared and not as united as the Palestinian Jewish side. There were several months of static local attacks and ambushes, until the Jewish side realized that going on like this may end a failure, so they started a series of attacks on April 1948 that ended with the Palestinian Arab mostly collapsing. At that point Palestinian Arab militias were mostly out of the picture.

Eventually a Palestinian state was eventually declared, in Gaza, in October 1st 1948, but thwarted in practice by Egypt and Jordan.

In 1948 Jews were roughly third of the population in the country. Nowadays Jews are roughly half of the population. I'm very suspicious of any suggestion for a plain single state. It is all to easy to make it go up in flame like in the end of November 1947.