Except DNA is not as “fixed” as all that. There may be some informational drift iin our DNa during out lifetime owing to our experience.
And humanity is not the end-all of DNA’s purpose. Solitary carnivores, herd animals, invertebrates of innumerable stripes have different strategies that work so long as their environments allow them to adapt, if necessary. Genetic drift also plays a huge role; as large as natural selection, I would say.