It is fairly evident that the U.S. is worried about China putting it in a position where it's not as easy/effective to go around the world, exploit foreign natural resources under false pretenses and sanction "non-compliant" nations to the brink.
It has absolutely 0 to do with human rights and all to do with economic power.
As for Chinese domestic human rights, the thing is doing coups etc. as was done so many times in i.e. the Middle East and Latin America won't lead to a better outcome because a coup is a forceful, violent and sudden, unnatural event that requires forces usually as bad if not worse than the current regime to pull off and denies the chance for long-term institutions to develop that adopt naturally by increasing human rights, however slowly.
It's the same problem with introducing modern economic theory, manufacturing, technology to a nation that did not had that trickle in at least somewhat continually over a period of time. It's a shock to the system in a way that rarely leads to better long-term outcomes.
There is a political theory that any transition from a repressive to an open society involves going through a risky zone of instability:
https://en.wikipedia.org/wiki/The_J_Curve_(book)
Now if you consider that this involves a country of 1.5B people, and take into account past experience with radical political changes (e.g. the Cultural Revolution), it seems that even for the most enlightened political leadership, both domestic and foreign, there may not be any easy answers how to proceed.
Or is it the case that the only time that human rights actually enact change is when there is an underlying material interest, making them little more than a veneer?
You can look at the glass is half full view of this, though - thanks to selfish interests an evil regime is being cut off from market access to spy on people around the world. Its of mutual benefit to the capitalists that saw this happen and the people whom China would have invaded the privacy of.
Of course that begs the question what Oppo, Xiaomi, etc are still doing in US markets... just because they are using international SoCs doesn't mean their assembly in China is trustworthy. But if you start asking those questions you start wondering about all the phones assembled in China by external companies like Apple or all the chips added to Samsung phones sourced from China, etc.
First, will isolating China from the US and it's client states actually do anything to make the CCP act in a way that will respect human rights more? I think it is pretty clear that won't be the case.
Second of all, is the entity that stands to benefit actually going to be better for human rights? In this case it pretty much is a zero-sum game. This is a bit more debatable, but I don't think that if the US won this Cold War against China the situation for human rights in the world will become any better.
Because of that, I can't get behind it, at all.
Second, the country that is now invading the privacy everywhere in the world (anyone forgot Snowden?) and raging wars without end in sight is the country pretending to be for democracy. This only tells me that the only greatness we still have in the West is the ability to spread propaganda. Somehow, people can be easily convinced that all this is for the greater good.
That's true, but you need to contrast it with the other outcome - if China wins, human rights everywhere are very likely to become much worse.
That itself is a really good reason to support the US / West.
By any measurements one can imagine, this was true since 1970s: China were rapidly liberalizing.
In 1970s Chinese cannot choose what they wear each day. That's how authoritarian it was.