In the context of this article, it’s humans inflicting adversity on humans that is the topic.
Yes, Nietzsche took a broader view. Nature itself is out to kill us. Struggling against that which would kill us, in Nietzsche’s view, whether nature or other humans, culls the weak and leaves the strong, driving humanity on an upward trajectory. He was reinterpreting Darwin, you see.
Nietzsche certainly addressed human-human conflict, and at great length. I think I haven’t misrepresented him.
Nietzsche has admirers, and his contemporary admirers have coined the term ‘Social Darwinism’ in defense of very specific policy goals. The eugenics movement emerged from these admirers, and Nietzsche is a perennial favorite of Nazis and White Supremacists, who imagine their genetic heritage to be superior to that of other races. (If they knew just how miniscule is the DNA that differentiates the races, would it give them pause? Probably not.)
The irony here is that Social Darwinism has no place in the sciences at all. It’s not *just* a reinterpretation of Darwin, but a fun-house mirror reinterpretation which distorts science beyond all recognition. For even more chuckles, observe that the very people who today push Social Darwinism are usually — not always, but usually — vehemently opposed to Darwinism itself. They’re science deniers.
I repeat: Nietzsche was an idiot. He was attempting the impossible: he was a nonscientist who didn’t even begin to comprehend what Darwin had written, trying to drag the theory of natural selection out of science, where evidence rules, and into the realm of philosophy, where evidence does not rule. Intellectually, he failed utterly. That sympathetic morons have flocked to Nietzsche over the years and echoed his message only demonstrates that he has plenty of moronic company.