I think it’s mostly an observation about unforced discontent, which is a notable (defining?) feature of human existence that’s apparently (at least) much rarer in the rest of nature. I doubt people much closer to nature, death, and killing than most modern OECD-state humans weren’t aware that animals suffer, nor that they must sometimes run to catch their food.

It might be worth interrogating the original language of the work, which I’ve not done. The translator may be depending on the reader’s cooperation here.