the powers that be (UK and US primarily) already have control of the area (still Mandatory Palestine), and a desire to maintain control of the area, they decide to give most of that land to the Jews and call it Israel.
Israel wasn’t created by the UK or the US (or the UN). Israelis declared the state of Israel themselves after seizing territory in the 1948 Arab-Israeli War.
The UN did have a plan to create an Israel in 1947, but that didn’t happen, because neither the Jews, the Arabs, nor the UK were on board.
They were young people who were gathered for a music concert.
Israel has compulsory military service for young people, so many of them were enlisted in the military. That doesn’t change the fact that they were young.