Remember that the Jews are just a small portion of the descendants of Abraham.
All those who came from Hagar through Ishmael, from his children with Keturah, and from the 10 northern tribes of Israel who were carried away by Assyria are also descendants of Abraham.
When the Lord promised him descendants as numerous as the sand on the seashore, he meant it.
Note that the promises to Ismael and Isaac were different:
The promises regarding Ishmael were that “He will be a wild donkey of a man; his hand will be against everyone and everyone’s hand against him, and he will live in hostility
toward all his brothers.” {Genesis 16:12} and that God would “make a great nation of him.” {Genesis 21:18} He did both of those through what would be come the Arabs.
The promise to Isaac was that God would “perform the oath which I swear unto Abraham your father.” {Genesis 26:3} God’s promises to Abraham continued through Isaac.
Yes, but that particular promise was passed down in the inheritance to Joseph... and from there to Ephraim and Manasseh. It is not for the sons of Ishmael.