Question
Was Abraham the first monotheist?
Answer
Abraham was the first Jew (or more precisely: the first Hebrew), but he wasn't the first monotheist. Some of the leaders of the generations between Adam and Terach were undoubtedly pagans, but some of them, especially Adam and Noah, were believers in the One and Only G-d. Noah's immediate ancestors (Chanoch, Mesushelach, Lemech) were also righteous, but they died before the Flood, so only Noah and his immediate family were saved.