So you found a Catholic Priest who was a descendant of David of Judah and Jewish. Interesting discovery, but misses the context entirely about the Levitical priesthood begin Jewish...
So does that now prove that because a few Catholic Priests are found to be descendants of David of Judah and Jewish - now does that prove that the Levitical priesthood has now established in these few Jewish Catholic Priests and passes on their Jewish blood upon all Levitical priest Catholics?
If a new priesthood was instituted by Jesus Christ, then this priesthood must be by definition above the level of Christ's priesthood, of the order of Melchisedec; but Christ said regarding HIS priesthood: it continueth [for]ever, [and] hath an unchangeable priesthood.
Now Christ Jesus's priesthood has performed these things: Hebrews 10:10 By the which will we are sanctified through the offering of the body of Jesus Christ ONCE FOR ALL [TIME].
I have yet to have a Catholic answer correctly about Hebrews 10:10.