From a Protestand point of view---Three things that God is that humans aren't...
1) Omnipresent - Everywhere at once. Can Mary hear and answer prayers from all Catholics, all over the world at once? Of course. A Godlike power!
2) Omniscient - All knowing. Does Mary goof up. Answer prayers incorrectly. You pray for healing, she misunderstands and you get herring? Never!! A Godlike power!
3) Omnipotent - All powerful. Can Mary desire to answer your prayer, but be unable? She lacks the authority to answer and refers you to God for an answer? Never!! A Godlike power.