Nazism was a haphazard mixture of all sorts of radical political ideologies, but predominantly right-wing.
The nazis were not left-wing or socialist economically: in fact, they didn't really have an economic plan. All they cared about was the rearmament, it was absolutely essential, and they were willing to sacrifice almost everything else to arm their military, even the welfare of the population, even the housing markets (which might've otherwise lead the recovery from the great depression in the private sector) and even public infrastructure like railways. The disrepair of the railways, which Germans were once proud of, evoked international commentary. Almost all railway cargos ran late (so much for fascists making things run on time!).
Politically, the nazis were extremely authoritarian conservatives. They explicitly promised the corporate sector that they would crush labor unions and leave private companies fairly free to deal with their internal issues. THe nazis carried through a program of forced business cartelization, which the big business welcomed warmly. Through these cartels the government worked with the companies. The resulting bureocracy was of course annoying to the business people, but they received very lucrative contracts from the government, so they didn't whine that much. In fact, Hitler consistently received his most fanatical support from the business sector. So, Nazi Germany was no a socialist country at all, it was more like a regime of the bosses.
Also, the nazis were not Darwinian. You don't need Darwinism to think in racialist terms. The nazis had a lot influence from agrarian romanticists. Now, any agriculturalist roughly knows how to refine races of different animals to suit some needed purpose.