“Survival of The Fittest” is a bit funny, because that’s explicitly not the evolutionary survival strategy humans (and many other animals) have taken. Humans organized into tribes because we’re stronger when we help each other. We learned how to speak because we’re stronger when we’re together and sharing ideas and knowledge.
And we have ample evidence that we took care of handicapped and injured tens of thousands of years ago, as long as we can be called humans. We did not get here by culling the weak, we got here by carrying our weak. Literally. Those that didn’t hunt and gather, had time to think and collect stories, make musical instruments and entertain others.
Rugged individualism is a sin against human nature, not altruism.