For every high priest taken from among men is appointed for men.... He can have compassion on those who are ignorant and going astray, since he himself is also subject to weakness.(Hebrews 5:1)
According to the scripture above, Melchizedek had to be human to serve as priest.
(Genesis:14.18) Then Melchizedek king of Salem brought out bread and wine; he was the priest of God Most High
Genesis 14 is a chapter dedicated to kings. Ten kings to be precise. The last of whom was Melchizedek. Since Melchizedek was king of Salem in Canaan;
Was Melchizedek, the king of Salem a Canaanite?
As a king, who were his subjects in the land of Canaan?
Did his priesthood serve any group of Canaanites at the time?