Are all Arab people descended from Ishmael?
No, not all Arab people are descended from Ishmael. Most Arab peoples come from Ishmael, but the context clarifies that other branches also contributed to the Arabian peoples. The statement explicitly says 'most,' not 'all.' Therefore, while Ishmael is the primary ancestor, he is not the sole source of Arab lineage.
Les explains that it is out of Ishmael that most Arab people have come, but he clarifies he did not say all—only most—because other branches also feed into the Arabian peoples. He connects this to the prophecy that Ishmael would be a wild man, his hand against every man and every man's hand against him, which explains why a Middle East peace prospect is dim and why these people are hard to deal with. He cites businessmen who dealt with Middle Eastern people confirming this, calling it an intrinsic prophecy of God about their personality. The context also records Hagar naming the Lord 'Thou God seest me' and the well called Dear Lehiroi between Kadesh and Bered, then Ishmael's birth when Abram was 86.