Well historicly they where jews, but according to the quaran, and the quaran only they where muslims.
Yes i agree with you, only according to the Quaran they were muslims. While children all over the world, also in East Asia and non muslim Africa i believe, know that Moses, Abraham and Isaac were Jews. They celebrated jewish holy days, and as far as i know before Muhammad's times there is No single historical verse about religion called islam, while there are hundreds of historical stuff about judaism and Jews.