Is the United Nations still relevant ?

It was created right after WWII, based on who was in the winner side and who was on top of the Military/Economy/Political/Diplo rankings. That's why the US, UK, France, Russia and China are the only permanent members of the Security Council and the only one who has the right of veto, meaning they can just close a vote before even it happening and without any reason.

Quick sum up of how the UN works : The general assembly has 193 members, and recommands actions/law/..., then the Security Council (5 Permanent members + 10 Temporary members (elected for 2 years)) decides what to do (i.e. sending the peacekeepers). And then the general secretary will be responsible to execute the decisions.
But whenever they want, the 5 Perm members can veto anything they want in order to protect their own interests. And as you may know, US / Russia / China are not really great friends with similar interests.

So are they really "United" Nations, or is it now an outdated idea that should be rethought ?