[Tzfat]

Jesus preached: "I come not to abolish the Law but to fulfill it." I suspect that to be the basis of what you call Supercessionism but,

Not true. Supercessionism is not about "fulfillment" it is about replacing the people, and G-d of the Bible, with a a new people and new god.

Messiah's comments in Matthew 5:17-19 use a common rabbinic formula (to make the Torah "stand up" or to support it). To "fulfill" is NOT to "abolish" (see His own words in Matthew 5:17), or to supersede (same as abolish, or replace). The Greek word for "fulfill" is used for a Hebrew word that means for it to be seen as standing up, or as it is meant to be. How anyone could supercessionism from Matthew 5:17-19 shows how denigrated biblical understanding has become.