If Muhammad was sent to all humanity, and the rest of the prophets to specific peoples, why was Moses sent to invite Pharaoh to worship God, even though Pharaoh was not from the Children of Israel? And would Pharaoh have had to follow the law of Moses, which was specific to the Children of Israel, had he believed? And was this an exception to the generality of the prophets’ messages?

Moses, peace be upon him, was sent to the Children of Israel, but they were oppressed by Pharaoh and his elite. Therefore, in order to free them, it was necessary to approach Pharaoh and invite him to monotheism first, so that he would acknowledge Moses' message and release the Children of Israel. It is repeatedly mentioned in the Holy Quran that Moses was sent to Pharaoh and his elite, not to the Copts, because Pharaoh and his elite were in control of the Children of Israel, and the goal was to save them. Thus, the primary message was directed to the Children of Israel, and the invitation to Pharaoh was a consequence, so that he would submit to Moses and free the Children of Israel.