We aren't born with rights unless there are people living at the time of our birth willing to fight for those rights. I mean, monarchy exists with supporters today despite being against the basic human rights you assert we are all born with.
Speed limits on roads exist; if someone's speeding, it's a question of enforcement.
Similarly, we're born with human rights as ratified in the UN Declaration of Human Rights. To your point, they're moot if not enforced -- I get that. But it's easier to enforce what exists than to fight for the original law.
We could be born with human rights as ratified by the Flying Spaghetti Monster and it would be just as meaningless. Enforcement is equally meaningless if there is no recognition of authority.
Why does the UN get to dictate human rights and not some other body? Did those human rights exist before the UN or not?