It goes all the way back to Greek philosophers such as Anaximander.
Darwin's concept of natural selection, in a simple sense, said those that developed some sort of functional advantage would be elevated and would pass it on to their offspring. Those that didn't would die off. Many on the left adhere to Darwin's mindset. Why do so many on the left support wealth redistribution programs if they do so. Wouldn't those, the weaker and less advantaged be left to die off under Darwin's theory?
This theory has been distorted in several ways, and indeed formed the major views of WW2 and the cold war beyond.
You voiced the view typical in America, and especially in the West at that time. Here, survival of the fittest meant innovation, drive, money, power. In other words, the weak should inherit what's left.
In Hitler's Germany, survival of the fittest meant anything pure Aryan. In other words, the weak should be excised from society, like they were a cancer.
In Stalin's Russia, survival of the fittest meant the government should decide who it 'fit', and the weak should be excised from society, like they were a cancer.
Note the similarity of Germany and Russia here.
Darwin himself simply noted that he felt that a species simply existed because it was best suited to survive. Other variations didn't survive in that environment because of this. This theory has been falsified.
Because Darwin's theory tended toward a single variation of a species, it completely failed to consider how those variations survived to select from. In other words, Natural Selection from a variation denies the variation to select from in the first place. Various folks try to rationalize their way around this, but this problem still remains. Further, there are quite a few species that have characteristics that do NOT help them survive, especially when compared to a more 'advanced' species that has a more limited version of a 'surviving' characteristic.
Example: Both birds and insects have a wider spectral response in their vision than we do.
Rats have only dichromatic vision (essentially like human red-green color blindness) and very faint color vision at all, and have a normal eyesight of about 20/600, yet survive by the billions.
Even the question of what is an 'advanced' species becomes nothing more than someone's arbitrary assignment. Since Man is primarily interested in himself, people generally list Man as the most 'advanced' species.
Yet, we can't fly. We have to build machines to do it. Having done so, we can fly higher and faster than any bird.
We can't run as fast as animals like deer or cheetahs, We have to build machines to do that. Having done so, we can go faster than any of them.
We can't make honey at all, but a lowly insect can. We have to steal it from them. We can't even farm many crops without these insects.
Is the domestic turkey a more 'advanced' species? It's larger, it's got more meat on it than their wild cousins, it's obviously surviving quite well...or is it? This bird is so distorted by us that it can't even breed. The birds no longer fit together. They have to be artificially inseminated. Is what we did to it something that is responding to survival of the fittest for the conditions that we imposed? How about the domestic cat? The domestic cow? Did you know that many animals, including birds, are completely dependent on a lowly insect, the bee? So are many plants. Are they 'less' than the animals that depend on these plants for their very survival?
How can one sensibly label any of these species, domestic or wild, somehow more 'advanced' than another?