Certainly the shahadah contained an important theological innovation, but that innovation was not monotheism. With this simple profession of faith, Muhammad was declaring to Mecca that the God of the heavens and the earth required no intermediate whatsoever, but could be accessed by anyone.
Ansar is an Arabic term that means helpers or supporters. They were the citizens of Medina who helped Prophet Mohammed upon His arrival to the Holy city. While 'Hussain' is a derivation of 'Hassan' that means 'GOOD' (I also owe this one to Khaled Hosseini). That's how my favorite character in my debut novel 'When Strangers meet..' gets his name... HUSSAIN ANSARI, because he is the one who helps Jai realize the truth in the story and inspires his son, Arshad, to have FAITH in Allah.