The teachings of Islam have been the same in Bible, Torat, Zubur, and all the divine Bboks.
Quran teaches the oneness of Allah. Hazrat Adam taught his children the same thing. It's just that the teachings were revived after sometime, when the people adopted the wrong path.
Islam started from Hazrat Adam, and Mosa revived it, Hazrat Sulaiman, Yaqub, Yousaf, Eisa (Peace be upn all them), and finally, Hazrat Mohammad (PBUH).
So Islam isn't a new religion. The teachings of Islam have been there from the time of Hazrat Adam(PBUH).