You've obviously consumed a lot of internet propaganda originating from Iran.

Israel's intent were actually genocide they could simply drop a nuke on Gaza and there would be nothing the UN could do to stop it. They don't do that because their intent isn't on genocide.

Also the UN cannot be in Israel without the consent of Israel. Nations have ultimate sovereignty over their territory there is nothing about the UN that supersedes national sovereignty. Seems you've also fallen prey to the "black helicopter" UN conspiracy theories, just you think UN black helicopters are a good thing. The reality is they don't exist, UN peacekeepers are only where they are because nations have agreed to their presence to observe the other party of a treaty (and will allow themselves to be likewise observed) to ensure they are complying.

You should take some time to learn about how things work in the world instead of just believing everything you read on social media. The can provide tools that nations can use to facilitate peace, but the nations themselves decide whether to use those tools.