Melchizedek - King of Salem[Peace]; King of Righteousness - or - Righteous King.
Mentioned first in Gen.14:18 and Recognized, and acknowledged by Abram who communed with Him. Scripture re-quoted in Heb.7:1
Psalms 110:4 "Thou art a Priest for ever after the order of Melchizedek." This Scripture is re-quoted in Heb.7:17, 21.
Reading the above Scriptures, and more of the versus, one can conclude for certain, just Whom this Melchizedek is: This is none other than Immanuel-Christ-Jesus as LORD of LORDs. The only High-Priest. The importance? Everything taught in the Gospel is about following this Priest. That is why Christ went to Jerusalem: to expose the Hypocrites[religion], and satisfy the penalty of death from the Garden.
Ex.2:1 "Sons of Aaron" = the Tribe/House of Levi chosen to be the LORD's priest - forever.
"My covenant of Life, and Peace is with Levi, says the LORD of host; Mal.2:4,5.
The Apostle Peter in 1Peter 2:9 explains just who the Chosen are.