alaykum salam akhi, I Ask Allah to bless you and reward you all good dear brother Osama, Allahuma guide us to help the truth rises over evil again and always, Allahuma teach us of what benefit us, and benefit us of what you taught us.
I'm very happy that it was a good article for the community... I ask Allah to guide us to more good articles for the sake of truth.
about Melchizedek, there are some apologetics tells that the biblical Jesus has advent himself in Melchizedek because Abraham ﷺ was giving him the tenth as in Hebrews 7, but some of them ignores Hebrews 7-3 which tells that he looks like the son of god(aha! isn't the one who looks like the son of god is another son of god?), but it didn't say it's him, so they tried to make it appears like the biblical advents on the tree and the pigeon without any type of biblical evidence also, just a words in the air like any rejecter who reject Allah orders through idols or science or anything else than Allah.
also they claim that the only and the first incarnation for their Deity was in the biblical Jesus. but I see that since Melchizedek looks like son of god with unknown genealogy, then he is also must be considered as an incarnation out of the house of david because where is it says that the incarnation has/will only happen in the house of david

so yes Melchi is still the fifthinity! the first incarnation maybe? until they have a biblical evidence of a verse telling that Melchizedek is really a biblical Jesus the first, not only looks like him, or any other biblical evidence telling us that Jesus was the only incarnation for their deity.
Allahuma reward you well .