Abraham was the first Hebrew. He had six sons with his wife, Keturah. Save for her son Jacob, Abraham's other sons descendants were all considered Gentiles. Which means they were the descendants of Abraham, due to his seed giving life to the five sons from whom the Gentiles sprang.
While the descendants of Jacob, his twelve sons, gave rise in this order to those that became first known as Hebrews, then Israelite's, and lastly, Jews.
The Book of Leviticus chapter 26:40 “But if they confess their iniquity and the iniquity of their fathers in their treachery that they committed against me, and also in walking contrary to me, 41 so that I walked contrary to them and brought them into the land of their enemies—if then their uncircumcised heart is humbled and they make amends for their iniquity, 42 then I will remember my covenant with Jacob, and I will remember my covenant with Isaac and my covenant with
Abraham, and I will remember the land. 43 But the land shall be abandoned by them and enjoy its Sabbaths while it lies desolate without them, and they shall make amends for their iniquity, because they spurned my rules and their soul abhorred my statutes. 44 Yet for all that, when they are in the land of their enemies, I will not spurn them, neither will I abhor them so as to destroy them utterly and break my covenant with them, for I am the Lord their God. 45 But I will for their sake remember the covenant with their forefathers, whom I brought out of the land of Egypt in the sight of the nations, that I might be their God: I am the Lord.”
46 These are the statutes and rules and laws that the Lord made between himself and the people of Israel through Moses on Mount Sinai.