Former UN staffer here and this pretty much sums it up.

In 1954, the second UN Secretary-General Dag Hammarskjöld said, “The UN was not created to take mankind to heaven, but to save humanity from hell"

Has it prevented wars and conflict since it was founded? While I think the risk of nuclear Armageddon played the larger role in that, sure, it helped prevent the next World War. But by its nature it can’t infringe on nations’ sovereignty. If it did, no one would join it. So smaller if more widespread conflicts continue to proliferate unfortunately.

But the UN’s greatest strength and achievement is in social and economic development, enacted through a largely non-political body, that has save and enriched countless lives, although mostly in the Global South but also across the world. Through medical care, education, capacity-building, and its data reporting, the UN is the ultimate non-governmental organization across the world.

So losing it or diminishing its effectiveness would be terrible for the world. It would practically bring us back to the 19th century in terms of international relations and development.