I didn't used to understand foreign involvement in wars, like the whole America-Vietnam shenanigans. But I can see why after watching this Israeli Palestine Conflict since birth.
But now it's like watching two children fighting over who's sandcastles can be built in the sandbox. And what do we do if children can't learn to share? You take away everything and no one is happy.
So is that what this is going to come to? Do adults need to intervene to quell the infants?
The problem goes back further. You say "another group owned it first", but Israel say they have had that land for millennia and it was given to them by God.
Palestine did not even exist until the British randomly carved it out on a map except for a brief period under the Romans around 0BC. The Romans called it Palestine in order to remove Israel's identity.