Again, I intend no sarcasm: have you ever asked someone if they will pray for you, or remember you in their prayers? The Bible says, “pray one for another,” then do to feel that doing so is or is not mediating in some way?
In Acts, when Peter said, “Silver and gold have I none; but what I have, I give to thee: in the Name of Jesus Christ of Nazareth, arise, and walk!” (I love that part!) wasn’t Peter a mediator?
Being an ambassador, which we are told we are, and praying for one another, which are are told to do, is not the same as being a mediator.
The Holy Spirit in Scripture tells us that there is only one mediator between God and man, Jesus Christ.
Your issue is with the word of God, not me for telling you what it says.