Excellent point
Humanity's greatest survival tool is cultural and intellectual evolution. No other species has this, and only very simple life forms like bacteria have physical evolution cycles that can respond as quickly.
Darwin emphasized the ability of a species to reproduce as a sign of evolutionary success. With humans, someone like Jonas Salk can make a huge contribution to the species even if he had never had children at all. The invention of language, and later, writing, allowed the human mind to become essentially immortal.