If Abraham, Isaac and Jacob are patriarchs, then what are Adam, Abel, Enoch, and Noah? If I understand correctly, the people in Genesis 12-50 are known as patriarchs (Abraham, Isaac, Jacob, etc...), but not the people in 1-11 (Adam, Enoch, Noah, etc...)

Is there a term that refers collectively to these primeval/pre-history type characters from Genesis 1-11?
The men you name are commonly referred to as antediluvian patriarchs, though Abel is not a patriarch, since Abraham was in Seth, not Abel. Antediluvian means "before (the) flood".