Look up Zoroastrianism and possibly others who are monotheists before Jews. An early monotheist who is not Jewish: Socrates. Greek! Hinduism independently has a concept of monotheism, also long before the Jews.
Monotheism is not efficiently spread by prophets or kings. They are lucky to get anything done without getting themselves killed. There is a famous monotheist pharoah at the end of the first Egyptian Dynasty. He proclaims himself prophet, turns against his national religion and tries to live peacefully with his family as an example to all, opposing war until the end of his days. Unfortunately for monotheism he is assassinated and also his heir, and one of his generals begins a brand new 2nd dynasty of polytheism.
Islam tends to conquer lands that are already monotheist. How is that spreading monotheism? Muhammad first appears in the Quran; but whether he writes it or some caliph does I cannot tell you. Apparently after his time the leaders of Islam cannot agree upon who is to be in charge, and the whole of Islam divides. How does this even count as monotheism if they are divided over who to follow? The same question can be put to Christians who have various divisions.
