The Absence of Prophets in Islam

Similar to how every product has a manual and a person who teaches how to use it, God has also provided us the Quran and the Prophet Muhammad SAW. Now, we have the Quran, but there has been no one after Prophet Muhammad SAW for the last 1400 years. So, my question is: Why has God not sent us more prophets? Not to change the religion in any way, but because we need someone to lead/show us. If God had sent us more prophets, the Ummah wouldn't be divided this much, and we would be in a better place. It seems as if God is saying, “I have done my job, now good luck,” and does not seem to care. Also, without us Muslims, very few people would be aware of Islam. Why are we supposed to spread Islam if God doesn't do it himself by sending messengers? For instance, after 1400 years, the majority in South and North America still don't even know what Islam is. Not to mention that between Isa a.s. and Muhammad s.a.w. there are 700 years with no prophets. Also as far as i know in islam there are messengers(Muhammad, Musa, Nuh, Isa etc. a.s.) who Allah sent rules/books and normal prophets who follow their previous messenger's book and teach it to the people. So why hasn't he done this for us, meaning send another prophet after Muhammad s.a.w. to guide us?