you are the same person who is saying that the order of Melchizedek has something to do with ancestry.
Now, the same original author of Hebrews is saying what is "even more clear":
if you think that a priest like Melchizedek appears, one who has become a priest in virtue of the his provenance from Judah, then you are going directly against 7:15-16. Since you, by mentioning Judah (with Moses, etc), are introducing a requisite to become a priest still and again in function of an earthly provenance. The exact thing denied by 7:15-16.
there is a function f such that f(Levi)= negative answer.
the original author and Giuseppe say: the function f is the problem.
Ben and the interpolator say: f(Levi) is the problem, f(Judah) is the positive answer.
Why, according to you, couldn't Jesus come from Levi? If he was from Levi, the author could avoid the apology about the introduction of a high priest coming from Judah against Moses. If he is doing so, the reason is not that a historical Jesus came directly from Judah so he couldn't deceive the his readers by saying that Jesus came from Levi. The reason is that the interpolator introduced Judah, since Judah was used by him against Levi, when really the original author was against Levi just as he was against any possible earthly tribe as provenance for the new Melkizedek.