Re Blacks and Jews. Jews fought for black civil rights and marched with them in the South, but on the negative perception side were also their landlords and shopkeepers, especially in the northern US. Also Jews of my parent's generation would have been quite dismayed if their daughter or son brought home a black boyfriend or girlfriend. Then there's the "schvartze" epithet, which thankfully is never used by my generation and younger Jews.
On the other hand I would never have thought to call a black person a negative name, but was called "Goldberg" by a young black man in Minneapolis when I started beating him in a $2 game of "9 ball" back in my pool hustling days. That was the last game we played...
An ally is not a friend.Apparently in the days of segregation, white-owned shops, restaurants, and apartment buildings would not do business with the black community. However, many Jewish business owners stepped in to fill this need. Unfortunately, many in the black community were frequently left feeling that they had been gouged or otherwise exploited by the Jews doing business with them, hence the residual animosity today from blacks towards the Jewish community.
The same hate groups that attacked black people, also hated Jews.