The Difference between Yishmoel and Eisav

"Rahav is celebrated as one... of the outstanding converts of all time together with Hagar, Osnath, Tzipora, Shifra, Puah, Pharaoh's daughter Batya, Ruth and Yael." Reply

The Talmud (Kidushin 18a) writes that Esau was considered to be a renegade Jew. This is not found concerning Ishmael.

You are correct, it cannot be understood on the most elementary contemporary level because the rules of who was Jewish had yet to be sit in stone. However, this is one case, where the current post-Mattan Torah rules were reflected in the pre-Mattan Torah reality as well. Hence, Ishmael—the son of a non Jewish woman (Hagar the Egyptian)—was not Jewish. On the other hand, Esau’s mother was the righteous Rebecca.

This is reflected in Sarah’s words, “The son of the maidservant will not inherit with my son, with Isaac (Gen. 21:10).” Reply

You mentioned a few times how Yishmoel was a Jew and Eisav was a non-Jew. How could that be if the Giving of the Torah had not happened yet? What do you mean by "Jewish". Reply