'Jewish' food is a matter of what Jews eat in different countries & how much they've adopted that cuisine. Jews are always amazed to find that I grew up on latkes. Well, they're actually called Sachsiche kartofflen (Saxon potatoes) in Germany, so they're not originally 'Jewish' at all; Poles call them platski (flatties). One young Jewish guy I worked with once said wistfully, "I wish I could have latkes more than once a year." I told him: "I had them often, because (most) Poles do." He was amazed. Poles eating latkes? Saxons eating platski?
Dunking German-Jewish pumpernickel into Polish chicken soup simply reunites what's already common to some Jews, some Germans, & most Poles. (Chicken soup is jokingly called 'Jewish penicillin' by Jews).
(flashback:) When I was young, my mother took me by bus across Lynn MA to a kosher butcher on Union St. in East Lynn to buy her chickens. She came from Salem, the next city east. 'Jack' the kosher butcher was the Nazi-cariacature of a Jew: big hooked nose, thick lips, big teeth, jet-black hair, etc. He must have wondered why this Polish woman came across town by bus for his kosher chickens. I assumed that's just where the chickens she wanted could be had. She, of course, never told me; I wonder what she told him? I assume it wasn't in Polish.