"Ancient scripture" says absolutely nothing about Metatron. He is a character from medieval Jewish mystical texts, long after any "ancient scripture" was written and the cannon (i.e. the Holy Bible) collected. The Bible was not assembled into a single book as it is now until later, but the Old Testament and the individual books of the New Testament were used in churches since the first century. Anything written later than that is not scripture.
Enoch is not Metatron, in spite of what Jewish mystics have claimed. Only humans are made in the image of God. Angels may have human-like faces or take forms like men when they interact with humans on earth, but they are actually something less than us, or rather less than what we have the potential to become. Turning a human into an angel would be a de-evolution and not in keeping with scripture.
From what we know of Enoch, he was apparently taken to be with God without having to undergo the agony of death. In other words, he ascended. Elijah also ascended. Elijah has returned to earth at least once since his ascension, at the Transfiguration, and he brought Moses with him. This suggests that Moses and Elijah have taken the same form since leaving earth, so the logical assumption is that all humans will take or have taken that form, including Enoch. Jesus ascended, but only after raising from an actual death. Enoch and Elijah, as well as those resurrected after the crucifixion, exist in the form that all of the Elect (i.e. true believers and anyone Go chooses to grant mercy) will take when we are either resurrected or taken up as Enoch and Elijah were when Jesus returns for us at the Second Coming.