You forgot to mention Friedrich Engels, the non Jewish Co founder of Communism.
Is there any proof that Communism was “disproportionately popular among Jews in Pre WW2 era?”
Re: Point 2, this wasn’t the case, as shown by the following.
according to 1928 statistics of the Polish Elections, Jews overwhelmingly voted for the Pro Government Non Communist Bloc. (49%). The next group they tended to vote for were Minority parties (33%). Only about 7% of Jews voted for Communist parties.
during WW2 itself, the overwhelming majority of Polish Jews chose to stay behind in Nazi Occupied Poland rather than “escape” to the USSR, based mostly on their bad experience of Russian Pogroms and the Germans liberating them in WW1. The same pattern was repeated in some rural Parts of Ukraine and Belorussia, with Jews generally welcoming Germans rather than fleeing to USSR, in part due to dislike of Communism and because the Molotov Ribbentrop pact led to the censoring of all anti German Propaganda, including info about Nazi persecution of Jews.
Poland is especially significant due to being the home of the largest Jewish population in Europe.
the same is true for Germany. Most Jews tended to be either Left Wing Social Democrats, or German Nationalists. Viktor Klemperer even tried to enlist when the Anschluss occurred, but was refused due to his Jewish Heritage.
This seems to be a loaded question, and the two key assumptions have been disproven. There was always a current of Antisemitism the territories making up the USSR, dating back to Tsarist times. It was reduced but not entirely eliminated by the USSR, since it continued to crack down on Jewish Religion and Culture by closing down synagogues, banning Zionism and the like. The main catalyst for the resurgence of Antisemitism after WW2 was Israel’s decision to stay Neutral after 1948. Stalin’s USSR was the main backer of Israel. They were the first to support partition, the first to recognize Israel after they declared independence, and were the only Nation to provide them Weapons in 1948. Stalin did this in the hopes of undermining Britain and believed that “the Jews” would “owe him one” and grant him access to the Middle east. This wasn’t the case. Not only did Israel declare Neutrality and distance themselves from the USSR, but Soviet Jews sent to spy on Israel ended up defecting to Them. Stalin was a control freak and a paranoiac, and he took this as a personal betrayal. This was not helped by the Simultaneous occurrence of the Marshall Plan. Stalin was quoted to have said that “Jewish Nationalists are spies and agents of American intelligence”, and interpreted the Marshall Plan, i.e. the funding of his Enemies by the US, and the alleged “betrayal” of Israel, as confirmation of this, that “the Jews” pulled one over on him. Another factor was the fact that many Soviet Jews supported the creation of Israel. Classic Russian Antisemitism always saw Jews as “Aliens” who were not loyal to Russia, and this was seen as confirmation of that. Hence, Stalin began his own Antisemitic campaign as “payback” against Jews for their perceived “Betrayal”.