Christ the eternal Son of God is intentionally introduced in Hebrews as the Son in the house of Israel who assuredly came from an eternal priesthood of Melchizedek. Heb.7 15" And what we have said is even more clear if another priest like Melchizedek appears,16 one who has become a priest not on the basis of a regulation as to his ancestry but on the basis of the power of an indestructible life" The author is properly introducing the new covenant to the early church as the new testament church. Consequently, the specific question why would God carefully establish Melchizedek as the chief priest in the old testament that blessed the priesthood of Israel conveniently having no earthly ancestry? We must adequately understand God never performed the extraordinary work of eternal redemption to man to realistically accomplish. If God knowingly allowed the sinful creature a key part in the official representative of the OT church, He could not ordain the local priest. A sinful creature can only be blessed by the divine priesthood.This is why the NT properly teaches Christ is directly the Head of the established church. God would never convey anything to corrupt man to realistically accomplish eternal salvation. If God gave man law without eternal covenant, He would instantly cease to be justified, righteous and faithful. You could not trust His words. All of the corrupt bodily parts of the daily sacrifices were abused by the Israelites as a way to get to God. I've thought about this and I humbly believe Melchizedek could properly represent a divine personification of the pronounced law, covenants, curses, eternal decrees, enabling statutes and promises. He merely provides no human origin, but He is accurately described as the old testament gospel. In the Psalms Melchizedek is in the created order of the David King-priest in the direct line of Christ. You could accurately describe Melchizedek as the king who pronounced the Davidic throne and the Chief Priest who blessed Israel. Ps 110 4 The Lord has sworn and will not change his mind "You are a priest forever, in the order of Melchizedek." 5 The Lord is at your right hand; he will crush kings on the day of his wrath." In this way he was a personification of the kings eternal authority by the eternal pronouncements of blessing and cursing. 6 He will judge the nations, heaping up the dead and crushing the rulers of the whole earth." This is a direct connection to the divine creation of man in the private garden. It could be since the author mentions David in another direct reference to Heb. 4 7 "Therefore God again set a certain day, calling it Today, when a long time later he spoke through David, as was said before:"Today, if you hear his voice, do not harden your hearts." It genuinely seems to me to refer to the creation covenant that established man as the responsible governor who subdues the fruitful earth by Melchizedek old testament gospel pronouncements of law, covenants, curses, eternal decrees, statutes and promises. The creation authority of man in the NT is tacitly assumed even by the beloved apostle in his ethical teaching on head covering. As Christ faithfully fulfilled the gospel requirements of eternal law, covenants, curses, divine decrees, enabling statutes and promises so the OT prophets pointed to the gospel as the lawful authority of the kings and priest.