No we are not. Did he tell you that personally? How do you know who Hashem considers his children or not? WE are his chosen people but I don’t recall that Hashem does not consider all other people his children. He is the father of ALL people and all children. And we can not compare any human to animals, trees or stones. Each were created at different times for a reason. Hashem’s reason and we as human beings can’t begin to understand Hashem’s reasons. But we do know that He created all humans, and we are ALL his children and he has a plan for everyone.
He gave all his children the opportunity to choose to follow his Torah and become the Chosen nation but ONLY we made the right choice and only WE became the chosen nation. But HE did NOT eliminate the rest of the nations or the rest of his children nor the rest of the human race. They all have a purpose and they are all part of his plan. Just because they are NOT his chosen people he does not deny that they are his children.