Would Jesus have approved of the Holocaust?

[True Federalist (진정한 연방 주의자)]

Given that the Old Testament is filled with story after story of the elder brother(s) incurring JHVH's wrath in some fashion and being dispossesed in favor of the younger, the idea of JHVH abandoning the Jews in favor of somebody else isn't all that far fetched.  The very last thing you want to be in an Old Testament tale is the first born.

[True Federalist (진정한 연방 주의자)]

But weren't Enoch (taken directly into heaven without experiencing death), Noah (the only righteous man found on earth), Abraham (the father of the faithful and the recipient of God's inheritance), and Jesus (Son of God) all the first born?

I believe you're taking a handful of cases (e.g. Ishmael/Isaac, Esau/Jacob) where the firstborn was not the child of promise and making too broad of a conclusion.

Well first off, note that none of those did anything to displease JHVH, but you're also forgetting Cain and Abel, Adonijah and Solomon, and even in an indirect way Leah and Rachel can be considered part of that same OT theme of its better to be young.  Note also that Moses was the younger brother of Aaron, and certainly don't forget that JHVH killed all the first-born of Egypt.