Once sentience is considered a continuum, you can say things that we kind of felt all along like "its less morally bad to eat a chicken than a dolphin".
The reason that this meets resistance is because it forces the question "is it morally bad to eat the chicken at all?" and then we have to pick a spot on the continuum as a dividing point. There may be some small disagreement as to where to draw this line...
Almost enough to make you shudder and try not to think so much.
We do not follow universal, perfect rules. Humans make judgements on what is appropriate or not based on preference.
It would be perfectly in keeping with sanity and normal behavior to decide something is worth the regrettable extinction of an intelligent species, while maintaining actual codes of morality.
More resources for us.
Humans on the other hand will pursue the illogical course of self-destruction for the slight chance of "moral victory."
That's not abandoning ethics, just changing them.
The holocaust is something we almost universally consider unethical today, but it was within the nazis ethical framework.
Questions I'd ask would be along the lines of questioning whether or not there were actual ethical principles at play, and if so what were they? I'm not sure that racial or national supremacy is really meaningful when you're not the person believing in it. "Race" for example isn't a particularly rigorous concept, so what ethical structures could you build around it?
Anyway, the system overall appears consistent to me: glorifying nature and culture. They have made advances with respect to animal-wellfare and protection of nature that we still benefit from today in that (a) they the raised the bar at the time and (b) the laws introduced then are still in place (when slightly modified).
They also introduced the first of a kind wellfare system for Germans and put a strong emphasis on family.
If you can understand and read German, this is a great documentary: https://www.youtube.com/watch?v=3vtfdfILdAw. It's funny just how much less tainted that documentary is then what we get to see to today.
I think there's a lot of hearsay about Nazi Germany and virtually anything you read on it is tainted either with hatred (99% of us) or fanatism (1%). I used to absolutely hate on the system, because no wonder, we are brought up in school to hate it just based on emotion and bad imagery. If you've read 1984 by George Orwell, going to history class in a way felt like the two minutes of hate. For example, there's plenty of evidence that Hitler did not want a war and tried his best to avoid it, yet in school it was already clear without a doubt that Hitler wanted a war for "world domination" or some none sense like that. Again, if you understand German, this is fantastic: https://www.amazon.de/1939-Krieg-Anlauf-Zweiten-Weltkrieg/dp... and a talk here: https://www.youtube.com/watch?v=lJuvWn7TFdY.
That should have implications for our species, if we let it.