Blessing and curses were never the starting point of God's, even in the Old Testament. Look at the opening of the story of Abraham in Genesis 12:1-3
Now the Lord said to Abram, ‘Go from your country and your kindred and your father’s house to the land that I will show you. I will make of you a great nation, and I will bless you, and make your name great, so that you will be a blessing. I will bless those who bless you, and the one who curses you I will curse; and in you all the families of the earth shall be blessed.’
We don't know why God chose Abram rather than anybody else. It's a spontaneous divine blessing to Abram first and to every family of the earth second. There's no suggestion of any kind of relationship that equates to a master and a paid servant.
I would suggest that like the melodies of a great piece of orchestral music, the same themes unite the whole Bible, growing in richness, texture and intensity as it unfolds.