I disagree. Let me post another scripture:
Heb 12:24 And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel.
The bible says right here that Jesus Christ IS the mediator of the new covenant. The word translated "mediator" is:
mesites
Thayer Definition:
1) one who intervenes between two, either in order to make or restore peace and friendship, or form a compact, or for ratifying a covenant
2) a medium of communication, arbitrator
In other words, Jesus the Christ was the one who ratified the new covenant.
A covenant is an agreement between two or more parties. The new covenant is between God the father and the houses of Israel and Judah:
Jer 31:31 Behold, the days come, saith the LORD, that I will make a new covenant with the house of Israel, and with the house of Judah:
Heb 8:8 For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah:
The bible even defines exactly what the new covenant IS:
Jer 31:33 But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people.
Heb 8:10 For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
The new agreement, the new covenant, is that God will write his laws in our hearts and minds. The terms of the old covenant, the ten commandments, were written on stone. The terms of the new covenant, the ten commandments, are written in our hearts and minds so that we are able to keep them spiritually and physically.
IF (and it's a big if) the ark of the covenant in Revelation 11 symbolizes any person then it symbolizes all Christians. The ark of the covenant carried the ten commandments, God's laws. Christians carry God's laws, the ten commandments, written within. But I think it symbolizes just how important are God's law.
(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.