And it is yet far more evident: for that after the similitude (ομοιτης [BDAG: state of being similar to something likeness, similarity, agreement] of Melchisedec there ariseth another priest. (Heb 7:15)
Commenting on the relationship between Melchizedek and Jesus, Protestant New Testament scholar Donald Hagner (correctly) notes that Hebrews does not teach that Melchizedek is a “Christophany” (Old Testament appearance of the pre-incarnate Jesus) but is a type of Jesus:
As a king and priest, Melchizedek is a type of Christ, not a preincarnate manifestation of Christ. The description of Melchizedek as being “without father, without mother, without genealogy, having neither beginning of days or end of life,” refers most probably to the fact that his origins are unknown (7:3; cf. 7:6), as are the dates of his life and death. Note well: he resembles the Son of God (cf. 7:15); it does not say that he is the Son of God. Our author stresses the greatness of Melchizedek (7:4), who blessed Abraham and received a tithe from him. Even Levi, “in the loins of his ancestor” Abraham, could be said to have paid a tithe to the great Melchizedek (7:10). (Donald A. Hagner, How New is the New Testament? First-Century Judaism and the Emergence of Christianity [Grand Rapids, Mich.: Baker Academic, 2018], 141, italics in original)