(sigh)
All that writing, and you didn't even address the fact that Jesus tells us HE is the New Covenant in Matthew, Luke and Mark. Frankly, everything you say I have no problem with. Jeus is the mediator of the New Covenant. Yet, it was His death and resurrection, the spilling of His blood, which signifies the Covenant. Frankly, the Ark of the Covenant did NOT contain the actual Covenant between God and the Jewish people, the actual agreement. It contained, among other things, the Ten Commandments -the signification of that Covenant.
Also, I have no problem with considering all Christians as the Ark of the New Covenant, though I believe St. Bonaventure was closer noting that the specific reference in Revelations could signify Our Lord, Himself. For example, the rod of Aaron signified the sacradotal nature of his calling in the same way Jesus is our High Priest.
However, the point remains: the symbol of signification of the Old Covenant were the stone tablets, the Ark carried these. By the same token, the signification of the New Covenant was Jesus Christ, and it was Mary who carried Him.
(double sigh) :-)
At the risk of being called picky, no Jesus doesn't say he is the new covenant. He says that his blood is blood of the covenant. His shed blood is the ratification of the new covenant for all that believe. Yes, belief in Christ is instrumental to the new covenant, but he is not the new covenant. Again, scripture tells what the new covenant is:
Jer 31:33 "But this is the covenant which I will make with the house of Israel after those days," declares the LORD, "I will put My law within them and on their heart I will write it; and I will be their God, and they shall be My people.
The new covenant is this: God says he will write his laws in our hearts and minds. It is ratified, accepted by us, by accepting the shed blood of Christ.