In the first place, your 'usurpation' is a bit presumptuous. You have no ability to usurp anything that is Christ's.
Secondly, while you are welcome to try, any intercession you might make before Jehovah standing upon your own name will come to naught. Standing upon the name of Aaron, in the way of the Levitical priesthood is also without merit. You may stand upon Peter, or any apostle, Mary, or any saint, the power of castle grayskull, the great doorknob, or the devil himself... Bupkis.
There is only Christ. Jehovah has hidden Himself from all others, as they are a stench in his nostrils.
And by the way, assuming intersession of saints for the sake of argument, If one knows the name of the High Priest, having a personal relationship with Him, what other name would better suffice? What shepherd shall we call to but our own? Why would one place a call to the advertising department when one has the private number of the CEO? It seems a bit silly, doesn't it?
Our prayers, be they praise, forgiveness, intercessory for others, or whatever, are all offerings before the Father. They ALL must pass from us to our Priest (intercessor), to the Father. We are unworthy to access the Father without the intercessory power of our Priest. That is why we pray in his name, and no other name will do.
So no, your intercessory prayer does not 'usurp' anything, nor does it in fact intercede. You ask in Christ's name for Jehovah to intercede as an offering of faith.
Finally, I think that prayers of intercession are quite like an act of forgiveness toward someone who has harmed you personally:
That act of forgiveness is seldom known to the person one is forgiving, and has no real impact upon that person's life. The act of forgiveness has much more influence upon oneself- It heals one's self of anger and fear, distrust and self pity. It causes one to put the matter to bed and to cease dwelling on the offense. It is really profound, and worth understanding.
Likewise, I imagine an intercessory prayer is of little real effect in the presence of an eternal, omniscient, omnipotent God. He already knew the score, and was already inclined to help, no matter who one might be praying over, or why. Does He need us to draw attention to the plight? Would He have forgotten that soul's cries had we not reminded Him? Are we not just an incidental tool in this way?
But that act of caring and belief does much within oneself to form a contrite heart, ready for supplication. Belief brings more belief, caring brings more caring, and so it goes. As is always the case, selflessly focusing upon others before God winds up helping you more than them.
Hey, I'm not the one that claimed "The role of the intercessor is the same thing as the role of a priest," so don't expect ME to make sense out of it.
Why would one place a call to the advertising department when one has the private number of the CEO? It seems a bit silly, doesn't it?
Not at all. One does not treat their sovereign like their "go-to-guy." The Scriptures tell us in many places to be cautious in the presence of the King.
Likewise, I imagine an intercessory prayer is of little real effect in the presence of an eternal, omniscient, omnipotent God.
Which is why we ask the Blessed Virgin Mary to interceed for us. The Scriptures clearly state Jesus told the BVM "mine hour is not yet come," but He changed the divine plan for His first miracle to accommodate her. NO ONE else in Scripture evinces such a profound influence on the Almighty for such a pedestrian problem.