But that doesn't explain why he needs to single certain people out.. seems like manipulation of a religion that has been swallowed down by the less dominant families.
Let me try to re answer the first question again.
If we are all Gods children... why did he select Abraham and his family?
Short answer (from scripture) God called and Abraham listened, and did what God told him to do…Starting the covenant.
The longer answer is in Talmud. Abraham’s father was an idol maker; all the people in the land worshiped many types of gods/idols. Abraham (having never before this heard the call from (The God) knew the idols were not real. He made fun of them and put food in front of them watching them for hours to see if they would eat, when they didn’t eat, he made fun of them and insulted them. Then he smashed all of his father’s idols, making his father very upset. It was after this that God noticed Abraham and made a covenant with him. The covenant promised that the whole world would be blessed because of Abraham and through his seed would come the Messiah who would redeem the whole world.
I would not say it’s singling out people. It’s not like only blue eyed people can be redeemed or only red heads. It’s anyone who wants it. It’s free to anyone who says I want to be part of this covenant. Through out the story many different people join in the covenant. Some were non believers before; some were believers in something else.
But by joining this covenant you did certain things. Ate certain foods and didn’t eat other foods, wore certain clothing. God said His people were a peculiar people, unique. This is how the world would know who His people are, by the way they kept them selves.