I like the first part of the story, but the latter half feels a bit rushed to me.
The happy aliens just issued a final ultimatum, and humans coincidentally found a way to sacrifice themselves to stop aliens.
Here are some random thought on a different ending:
They made a deal.
The happy aliens built a hyperspace glory hole in each city on earth.
Humans can voluntarily use these glory holes to exchange genetic material with them.
This exchange leads to ultimate growth of wisdom and ultimate happiness.
In the end, most of humans accepted such an exchange and become...
Personally, I believe the main problem is that the Qin and Han dynasties led China into a local optimum. And they stuck in there for a thousand years, they made minor fixes but never tried to replace the entire system.
We may even be making the very same mistake today.
Let's suppose, in the future, Earth were able to develop a utopian government, where everyone have complete freedom and zero life pressure, allowing everyone to freely express their creativity. Would those future people think we wasted our best brains in the number games of Wall Street, just as we think ancient Chinese wasted their best brains in the word games of imperial exam?