Yes, they do have more representation per capita. That's not political philosophy, that's math. You can keep talking about how the states are represented in the Senate, but the reality is the states are proxies for the population. It is, or at least should be, the people who are being represented by the Senators. The Senate votes on the same shit the House does. The states - the number of them and how they are split - does not conform to any moral, ethical, or political ideology. When you are basing a system on how the states are split, you are creating a system that lacks any moral, ethical, or political ideology on how representation is established. You think the current system just magically evolved in to how you would have done it? Ok. I have a hard time believing that. No more states. No fewer states. West Virginia should be separate than Virginia. Rhode Island should have equal representation to Texas, despite the vast differences in land area and population. Etc. This is how you would have devised it? Ok.
No, I don't think China should have 4 UN SC votes. I also don't think the UN is analogous to the US. Is there any confusion on that? Do we really need to dive into the differences?