Instead of a futuristic story, this seemed like an allegory of how our world came to be.
I think there are numerous theories as to what it's trying to say, but the biggest one appears to be to concentrate on today and not some end goal or the future you so much.
Cause ultimately it's all for nothing, and only the experiences along the way matter.
Humanity in the story suffered for a billion years, created massive empires, were destroyed, struggled to come back, built a huge interstellar alliance, which was destroyed and in the end the entire species just ceased to exist anyway.
aka don't fixate on your career and things like that so much, take some time to smell the roses and get more important things fixed in your life today. Cause the older you get the harder it is to sort those things out, things that matter far more to you as a person than you can probably understand right now.
A twist of the story is supposedly that the Qu are actually the final evolution of humanity itself, after a billion years they mastered time travel and went back in time to fiddle with creatures in the past. They found humanity and didn't even know these people they were messing around with were their own race in the past. So by messing around with them, they were in effect destroying themselves in the future.
So another theory as to what it's saying is we are too inquisitive for our own good and curiosity will one day kill the cat, especially due to how much power someone has over the entire world based on how many zeros they have in their bank account.