In defence of the UN, the UN schools in Gaza are rare sites of hope in normal times and invaluable lifesavers these days. And I have friends in the UN who were working their ass off trying to improve the situation even before the war broke out, and who I'm currently trying to convince to get some sleep between turns. The fact that the UN cannot work as a world police (except under exceptional circumstances and sadly so far strictly theoretically) doesn't mean it does not have an important role to play.
It's incredibly flawed, but it's what we got, and at least that's something.