Moses is alive.
The saints are alive.
Jesus Christ is the Way and the Truth. None come to the Father but by Him. That is how He is the sole mediator.
Mary and the communion of saints are subordinate to Jesus, but through His grace and His merits, they are allowed to cooperate with His plan of salvation, and so are we allowed if we pick up our cross and follow Him.
Not only is Jesus God of the living, he also is not a lonely God. He surrounds Himself with His mother, angels, saints for His glory. "Give us our daily bread" Does this sound like a God who does not want us all to cooperate in the salvific plan together?
From the cross he gave humanity His mother. When soldiers are wounded they often cry out to whom? Their mother. This is about love. Love asks us to empty ourselves for God and for our neighbor. How much more can Christ’s plan be made more clear that we are a community before God? Love is a communial emotion, not alone. The Trinity trumpets the Truth of communal love.
Of course we should pray for one another and pray to our spiritual mother and the saints in heaven to intercede for us and our loved ones. Of course we should worship God and God alone.
Both truths are beautiful and complimentary.