No DF, though i hate to disagree with a part of what you said. Ishmael was the son of Abram and muzzies claim a common God and heritage from it.
Actually it isnt me disagreeing with you but well respected christian bible scholars i happen to agree with.
Abram was reborn, remade and renamed Abraham. Ishmael was Abrams first son, not Abrahams first born.
Also, God had prophecied Abrahams son (if iirc the first) would be the lineage of David and Jesus though i dont remember the exact scripture.
I will admit there is room for disagreement and you may be right, but too many dont associate the name change as having any significance.
I see what you're saying, Abram vs. Abraham. Abram representing the fleshly man, Abraham the regenerated, Spritual man. One could say Ishmael was first born of the flesh, Issac was first born of the Spiritual.
Or, as in the first Adam vs. the last Adam (Jesus), there are types and shadows of "first the flesh, then the Spiritual" thruout the Bible.
Esau/Jacob, Saul/David, Manasseh/Ephraim, there are a number of "first the flesh, then the Spiritual" examples in Scripture.
DF