Why is God just called God?
God has a number of names, not just one; and each of the names signifies one of the ways in which God relates to this world. In English, some examples are God, Lord, Almighty, Creator, Father, and King of kings.
Because in Christianity it is believed that God inspired the writers of the bible directly, so the person is just the writing instrument and God is the author. This is called Divine Inspiration. Others believe that God spoke to them and told them what to write. This is called Divine Revelation, where God reveals himself.
She was called the little flower because Love of God as a Father, expressed in childlike simplicity and trust. which means she showed her love for God as a child would so she is called the child of Jesus. And the "little Flower" was just a nickname for her because she was young and delicate St. Therese of Lisieux loved flowers and often called herself "A lttle Flower of God."