Mary is the first saint, and holds high honor today, as she did in the early Church. Over the course of history, devotion to Mary has taken many forms, and even has been confused with worship. Church teaching has consistently placed Mary in the company of the saints, however.
Devotion to the saints comes back to the theology of image: Christ is God's image, the saints are Christ's image. We honor them because we desire to imitate them. We pray to them the same as we call upon earthly friends to do a favor for us. This too, is scriptural. In Acts we read of Peter and John going up to the Temple for prayer and encountering a beggar. Peter says to him, "I have neither silver nor gold, but what I do have I give you: in the name of Jesus Christ the Nazorean, rise and walk" (Acts 3:6). Peter makes it clear that he has the power of Christ in his possession.
“Peter makes it clear that he has the power of Christ in his possession”
As do we (saints), all. What we lack is sufficient faith.