As to Jews-as-a-Race:
Certainly the idea predates the 1930s and yet one must see that the real victory of Nazism was/is, despite losing the Second War, the embedding in the post-war mind the acceptance of the idea, no matter how ludicrous.
Yet no idea, however preposterously anti-scientific as the Jews-Are-A-Race idea is, can exist, let alone flourish, in a vacuum or without historical antecedents.
Prior to Racial anti-Semitism taking hold under the guidance of the Nazis, there was Political anti-Semitism, the forced removal of Jews from (largely European) regions and nations. This kind of anti-Semitism is about borders, lines on political maps.
Before that, anti-Semitism was largely what can be called Religious anti-Semitism: convert-or-leave.
In short, Religious anti-Semitism says You May Not Live Here...As A Jew. (There are nations, now, where this is law.)
Political anti-Semitism says to Jews... You May Not Live Here. (And there are nations, now, where this is law.)
And w Nazism, these positions built on one another, making explicit the assumption in the prior stages, that Jews are simply and fundamentally unlike others, that Jews are not fully human, that Jews are racially sub-human, as a matter of 'blood'.
Racial anti-Semitism is the ideology that says to Jews...You May Not Live.
That ideology exists today, less in nation-states as policy, though in nation-states as tenor and sanctioned, winked at and officially ignored behavior, and certainly among organized groups in state-sponsored organizations in various countries.
The benighted notion of Jews-As-A-Race is the ironic and far-too-potent enduring triumph of a formally defeated Nazism; it has its historical step-stones, and people who, today, speak of Jews as belonging to a race, whether or not they intend it, hold and further core National Socialist principles.
Most who entertain the idea, those who speak as if it is a creditable understanding and thus further it...they can do better and bring some needed credit to themselves.