Unlike Islam and Christiantiy, where you can point to one key figure, Judaism evolved. Jewish and Islamic traditions point to Abraham as the founder of monotheism, but the religion of Abraham would be unlikely to be recognized as specifically Jewish. The patriarchs Isaac and Jacob played a role, and Jacob, also known as Israel, was the father of the 12 tribes, known as the Children of Israel. Jews to this day identify as the Children of Israel, but until the Exodus and the events involving Moses at Mount Sinai, the Children of Israel were not bound by the covenant that is, today, taken as the defining feature of Judaism. So, who among all these do you identify as the founder? Each played a role in the founding.