Well, beyond Stalin not even being Slavic much less Russian, writings about Hitler’s foreign minister Joachim von Ribbentrop already made clear this preoccupation of Hitler’s. Hitler was convinced the Soviet leadership was predominantly Jewish, while Ribbentrop returning from negotiations in Moscow had to inform him that there were very few Jews in important political positions in Stalin’s USSR.
The Old Bolsheviks were heavily Jewish, and Stalin had almost all of them liquidated. I don’t think it was a racial thing; that’s just a typical revolution of the left doing its thing by eating its own.