It says there’s one mediator between God and man, who is Jesus. Where does it say otherwise?
I don’t like how I said that there is more than one mediator between God and man. Most Catholic theologians would say there is one mediator between God and man - Jesus. But they would also say that there are many intercessors between God and man - those on Earth and Saints in Heaven. The word intercessor more appropriately depicts the lowly/subordinate state of the Saints and Mary relative to Jesus and God. A parser of words might say that an intercession is a petitionary mediation, but I will not say that at this time.
So there are many intercessors between God and man (i.e. they intercede with God on our behalf):
1 Timothy 2:1 First of all, then, I urge that supplications, prayers, intercessions, and thanksgivings be made for all men,