In Europe until after the Napoleonic era, Jews could not be citizens or own land. They lived at the mercy of the lords and princes. Even when given major tasks by the European nobility, they still could not obtain citizenship or own land themselves.
Add to that the kind of tasks the nobility did give them
(because it was less threatening to the power of the nobility to give many important tasks to the Jew, ‘cause it could never gain him power from it),
like tax collector, manager of the farm & laboring serfs, {Ukraine and Eastern Europe), money manager, making investments for their lord.
From that Jews got a bad name from the common people - they were the taskmasters and tax collectors of the tyrannical nobility, providing additional social stigma and all the more reason they did NOT intermarry much. Though many Jews who had been given major tasks by the nobility advanced in the areas of their work - management, finance, investment - the majority of Jews were the lowest of the lowest and usually isolated socially. When was the Napoleonic Code adopted? 1804. Does that answer your question.
As well as the fact their high IQ level helped make them proficient in those tasks.
I learn something new every day.
What you have posted was very informative. And now that you bought it up, it makes perfect sense in regards to the anti-semitism that is part and parcel to European culture.
Like I said, if you don’t live it, you would never know. The European history that is taught doesn’t get that deep into the social stratification of these places, mostly just “who, what, when, and where”.