The Catechism in Questions & Answers

632. What does the address “Our Father” mean?

The address “Our Father” indicates that this prayer is a communal prayer. When people address God as “Father”, they bring to expression that He has created them, that He is their Lord, and that He provides for them. They can address God as “Father” without fear, in love, and in confidence.

Child of God: see explanation of Question 530.