My mother called her father “Daddy” her whole life, even when she was a grandmother.
She hadn’t been “dependent” on her earthly father for decades, but her use of “Daddy” showed a childlike respect, sweetness, affection, and honor.
The use of "Abba" is similar.
"The Spirit you received brought about your adoption to sonship. And by him we cry, 'Abba, Father.' The Spirit himself testifies with our spirit that we are God’s children." Romans 8:15-16
Abba translates “Daddy” or “Papa” – a term of endearment and childlike dependence. We also find it used in Galatians 4:6 and Mark 14:36.
God chose to relate to us as a perfect Daddy who, like good earthly fathers, gives us things that are good for us (Matthew 7:7-11), lovingly disciplines us (Hebrews 12:4-11), has compassion on us (Psalm 103:13), and cherishes us (Matthew 6:26).
When we become Christians, we have a God so approachable that we can call Him “Daddy” (Galatians 4:6). I find that amazing!