He latched onto existing prejudices against Jews that were popular in Germany since the late 19th century. Basically those ideas were already around but Hitler amplified them like 1000%. It was convenient I guess.
AskHistorians
They were often money lenders by trade, and I think he blamed their woes on this somehow
They were the political opposition, and the funding for it. He was an outsider populist. They were the establishment.
The previous government blamed Jews for losing WW1. It was called The Great Big Lie I think.
I believe youre referring to the Stab-in-the-back myth
The Jews at that point of time were viewed very similarly to how Muslims are viewed nowadays. Just like it now feels natural for many to assume that a Muslim is automatically a terrorist, back then people had very similar assumptions about Jews.
And just like nowadays populists can use "Look, a Muslim! Be scared!" as a way to get votes, back then they could do the same by saying "Look, a Jew! Be scared!"
it was an easy way to get people behind him. You can figure out what the sentiments people had towards Jewish people in 1920's were like if you just look at what the sentiments towards Muslims are in 2020's.