As for the title, “Ark of the New Covenant,” Christ is the Ark of the New Covenant.
Sorry for the delay in responding (busy week with work).
Nonetheless, you're incorrect on your assertion.
Christ is the New Covenant.
Mary, whose womb housed the New Covenant is the ark.
With due respect, to say that Christ is the Ark of the New Covenant degrades Him, as implicitly, the words "Ark of the..." implies that He is the repository of something more important than Him. Since Christ is the everlasting God, the second person of the Blessed Trinity, there is nothing more significant than Himself.