'Ancestor' in the Bible

What, then, are we to say about Abraham, our human ancestor?

Afterward he received the mark of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. Therefore, he is the ancestor of all who believe while uncircumcised, in order that righteousness may be credited to them.

He is also the ancestor of the circumcised those who are not only circumcised, but who also walk in the footsteps of the faith that our father Abraham had before he was circumcised.

Not only that, but Rebecca became pregnant by our ancestor Isaac.