Melchizedek and the priesthood
The first Melchizedek from 2nd Enoch was born not from the flesh, but from a "sterile mother", which means she couldn't conceive, not necessarily that she was still virgin.
Hence "...no father, no mother." For he wasn't from the father's, (Nir's) seed, but from God. No genealogy. No descendants.
It then states a man (Abram) would find in the mountain of Noah's ark another man (Shem) that was a recluse for 7 years. Shem was handed down the priesthood after the flood by Melchizedek, who during the flood was taken to the Garden of Eden and spared the deluge. There he was taught the ways of the Lord those seven years to Shem, hence Shem acquired the title Melchizedek.
From Shem to Abram.
Abram to Levi.
Levi to Aaron.
And the ultimate priest being our Lord. Amen. Thank you and God bless.