Your expectations are too high. The UN is a place where people can get together and talk, hopefully instead of going to war. That is why it was created.
The structure reflects the power of the actual countries in the world. The ones with bigger armies have more power. Nothing happens without the approval of the big guns.
The UN is not a beacon of human rights or justice or anything. If the members talk about that, it's because they want to talk about that. If they talk about Israel, it's because they want to talk about Israel. If you don't like what the UN talks about, you don't like the countries who are guiding that discussion.
The UN is to prevent another world war. We are not sure if it will be effective.