If you know Islam started from the first Human "Adam"
ROFL. So the first human being was a Muslim? Show some evidence to prove your claim. Was he circumcised? Did he prayed five times a day? I would believe you if you could show me the remains of the mosque, where he offered prayers.
The character of A muslim is praying for only One God. Adam Prays for Allah, Noah prays for Allah, Abraham prays for Allah, Moses prays for Allah, Jakub prays for Allah, Jesus prays for Allah, and Muhammad prays for Allah. Now, All people who prays for Allah only are muslims.