And Melchizedek, the king of Salem and a priest of God Most High, brought Abram some bread and wine. Melchizedek blessed Abram with this blessing: “Blessed be Abram by God Most High, Creator of heaven and earth.

Genesis 14:18-19

The LORD had said to Abram, “Leave your native country, your relatives, and your father’s family, and go to the land that I will show you. I will make you into a great nation. I will bless you and make you famous, and you will be a blessing to others. I will bless those who bless you and curse those who treat you with contempt. All the families on earth will be blessed through you.”

Genesis 12:1-3

• The original kingship of Jerusalem (Salem) does not go back to David, it goes back to Melchizedek. The original kingship of Jerusalem also entailed a priestly role.
• Hebrew origins of Melchizedek: Malkisedeq or malki-tsedeq (or tsedek). A hyphen in a name was unusual and more resembles a title. The name is formed by a noun melek (king) and a verb sadeq (to be just). 
• Dead Sea Scolls 11Q13 mentions Melchizidek
  ‍https://www.deadseascrolls.org.il/explore-the-archive/manuscript/11Q13-1?locale=en_US
  https://en.wikipedia.org/wiki/11Q13‍
• Philo, first century philosopher and commentator, refers to the encounter of Melchizidek and Abraham
  ‍http://www.earlychristianwritings.com/yonge/book22.html (235)
• Jospehus mentions Melchizidek in Jewish Antiqiuities
  https://intertextual.bible/text/genesis-14.18-josephus-antiquities-of-the-jews-book-1.10.2‍
• David recognizes the coming Messiah as being “a priest forever in the order of Melchizedek.” Psalm 110:4‍
• And God designated him to be a High Priest in the order of Melchizedek.
  Hebrews 5:10‍
• This Melchizedek was king of the city of Salem and also a priest of God Most High. When Abraham was returning home after winning a great battle against the kings, Melchizedek met him and blessed him. Then Abraham took a tenth of all he had captured in battle and gave it to Melchizedek. The name Melchizedek means “king of justice,” and king of Salem means “king of peace.” There is no record of his father or mother or any of his ancestors—no beginning or end to his life. He remains a priest forever, resembling the Son of God.
  Hebrews 7:1-3‍
• This change has been made very clear since a different priest, who is like Melchizedek, has appeared. Jesus became a priest, not by meeting the physical requirement of belonging to the tribe of Levi, but by the power of a life that cannot be destroyed. And the psalmist pointed this out when he prophesied, “You are a priest forever in the order of Melchizedek.”
  Hebrews 7:15-17‍
• Tell him, ‘This is what the LORD of Heaven’s Armies says: Here is the man called the Branch. He will branch out from where he is and build the Temple of the LORD. Yes, he will build the Temple of the LORD. Then he will receive royal honor and will rule as king from his throne. He will also serve as priest from his throne, and there will be perfect harmony between his two roles.’
  ‍Zechariah 6:12-13‍
• https://www.gotquestions.org/order-of-Melchizedek.html‍
• Jesus transcended the earthly roles of king and priest so that we would be a part of a heavenly kingdom. He chose to dwell with us as a descendant of an earthly lineage, but was not ultimately of earthly priestly or Davidic origins.  

Trust Jesus as king and priest, our perfect leader and mediator.