Yes they were!
They were perfectly happy saying they were much better than the average bear. And were often quite annoying that way.
Not a genetic super-breed, and note I said no such thing about myself. Whatever way I am better than you, it is a matter of normal variation and, most likely, the circumstances of life.
However, I am 5/8ths Basque, and we are an odd lot, with significant physiological differences vis-a-vis European and Euro-descended populations. That doesnt make us supermen, as we dont have the IQ data to conclude anything. It certainly isnt likely to challenge Jewish and Chinese superiority.
As for the Nazis and similar, they rarely claimed to be smarter than everyone. Strange but true. There was enough population IQ data out by then to show that Jews were on average, objectively, smarter. The Nazi claims were rather more mystical and aesthetic than that.