This is a complex question that depends more on perspective and values than factual lookup—but let me share a balanced view of the arguments on both sides, since this is a matter of ongoing debate rather than something with a single "correct" answer.
Arguments that the UN remains relevant:
•No alternative global forum: It's the only institution where all 193 countries can convene, negotiate, and coordinate on issues that no single nation can solve alone (pandemics, climate change, migration, nuclear proliferation).
•Humanitarian and development work: Agencies like UNHCR, WFP, UNICEF, and WHO deliver food, vaccines, refugee protection, and disaster relief to hundreds of millions of people annually—work that continues regardless of Security Council gridlock.
•Peacekeeping: Despite criticism, UN peacekeepers are still deployed in conflict zones (DRC, South Sudan, Mali's successor missions, Cyprus, Lebanon) where few other actors are willing or able to intervene.
•Norm-setting: Treaties, conventions, and frameworks on human rights, climate (Paris Agreement), and international law trace back to or run through the UN system.
•Diplomatic backchannel: Even adversarial states talk to each other at the UN when they won't do so bilaterally.
Arguments that its relevance is eroding:
•Security Council paralysis: The veto power of the five permanent members (US, Russia, China, UK, France) has repeatedly blocked action on major crises—Syria, Ukraine, and others—leading critics to call it structurally outdated for 21st-century geopolitics.
•Enforcement problems: The UN can pass resolutions but has no independent military or police force to compel compliance, so powerful states can and do ignore rulings against their interests.
•Representation gap: The permanent Security Council membership reflects the post-WWII order, not today's power distribution (no permanent African, Latin American, or South Asian seat, for instance).
•Rise of alternatives: Groups like the G7, G20, BRICS, and regional blocs (EU, AU, ASEAN) increasingly handle issues that might once have gone through the UN, especially when speed or like-mindedness matters more than universality.
•Funding and politicization: Member states, including major funders, periodically withhold dues or threaten to as leverage, undermining operational capacity.
My take: The UN's relevance is probably best described as bifurcated. As a platform for binding, enforceable action on major security crises involving great powers, it's often sidelined. As a vehicle for humanitarian aid, technical coordination (aviation, health, postal systems, weather), development, and as the only truly universal diplomatic forum, it remains hard to replace. Whether that adds up to "relevant" depends on what you think an international institution should be able to do.
If you want, I can look into a specific angle—like how the UN has performed on a particular recent crisis (Ukraine, Gaza, climate negotiations)—to make this less abstract.