Both. Hitler was just a part, but he was an integral part.

Germany has a long history of antisemitism, from Luther's On the Jews and Their Lies, to Wagner's Die Meistersingers, to Kaiser Wilhelm II proposing that left-wing elements and Jewish peoples worked together to topple his monarchy. The WWI general Ludendorff would also go on to claim the German war effort was "stabbed in the back" by Jewish forces and communists, and also participated in the failed Beer Hall Putsch of 1923. Most of the elements we would recognize today as proto-Nazi were in place. If you're curious for a more in-depth post on the "stabbed in the back" myth prior to the formation of the Nazi party, here's a post by /u/integral_grail discussing it in more depth.

From this, we can easily eliminate the idea that Hitler was the progenitor of Judeo-Bolshevism altogether. The pieces were already in place with the defeat of Germany in WWI. Hitler was obviously a fan of these theories, and gave them his particular expression in Mein Kampf. Mein Kampf became a best seller in Germany and informed the common perception of Nazi antisemitic myths. So while Hitler was not the one to invent the myths from the beginning, his expression was one of the more popular ones. Goebbels would go on to run the propaganda machine when the Nazi party came in power, who himself was dedicated to understanding and propagating Hitler's views on the matter. So yes, Nazi ideology was deeply informed by Hitler, but was created out of already existing popular perceptions.