Why was Prophet Ibrahim important for the Abrahamic religion?

First of all, I want to say I am Muslim, and my belief is that he was a Muslim; anyone who submits to God is a Muslim. But I am not here for that.

I just want to know why Prophet Ibrahim is important to the Abrahamic religions, as seen in Judaism, Christianity, and Islam. Why not Prophet Yaqub/Jacob, who had 12 tribes and became the Children of Israel? Then it was Judaism?

Where does Prophet Ibrahim come in, and how did it become an Abrahamic religion?