Number one, I’m not a musician. And number 2, yes they were Jews - certainly perceived to be in Russia. And I know many secular Jews who define themselves as Jewish, even though they never set foot in a synagogue.
What.counts in this case is.not the number of Jews.that there were in the Bolshevik party overall, but the high concentration of them in the inner circle, and the power that they wielded.
Among members of the Central Executive Committee of the Congress of Soviets in 1929, there were 402 ethnic Russians, 95 Ukrainians, 55 Jews, 26 Latvians, 13 Poles, and 12 Germans Jewish representation had declined from 60 members in 1927. With regards to Jewish representation in the ruling Politburo, it waned very rapidly starting in 1918. It began with the assassination of Moisei Uritsky, the most radical member of the Politburo, in August 1918. Then Yakov Sverdlov died of disease in March 1919 and Sokolnikov was shunted aside. Three years later in 1922, Jewish members in the Central Committee, the Politburo's new name, had shrunk to a minority of three : Trotsky, Zinoviev and Kamenev . Eventually they were all physically eliminated by Joseph Stalin : Zinoviev and Kamenev in 1936 and Trotsky in 1940. In the 1920s, of the 417 members of the Central Executive Committee, the party Central Committee, the Presidium of the Executive of the Soviets of the USSR and the Russian Republic, the People's Commissars, 6% were ethnic Jews.https://en.wikipedia.org/wiki/Jewish_Bolshevism#Jewish_involvement_in_Russian_Communism