Human rights, in my mind, are something that existed before the UN, and exist independent of the UN. And there's centuries of political philosophy that agree with me on that point. See, for example language like "endowed by their creator with certain unalienable rights" in the US Declaration of Independence. That tradition of political philosophy sees rights as inherent to humanity (in this case God-given, but it doesn't have to be), not guaranteed by some statement of a government or group of governments.