Yes it is very clear why God chose the Jews. I believe he did not choose every Jew but rather he chose the human line through Abraham, his lineage from which to bring forth the promised Redeemer, and the choice was made after testing Abraham.
Abraham was obedient and was willing to do that which God would do, to wit, to give his only begotten son Isaac by Sarah, to be sacificed on an altar according to God's command.
Abraham's obedience, although he was reluctant to obey, demonstrated his devotion to God.
Abraham and Sarah waited 900 years for a child and were without hope when Sarah miraculously became pregnant with Isaac. And then after Isaac was born and grew into a young man, God commanded Abraham to kill Isaac on an altar on a mountain. Although it was only a test of Abraham's obedience, it must have pained Abraham greatly who was not aware that it was only a test.
I believe Abraham's willingness and devotion to sacrifice his only child on an altar was a precursor to God's plan to sacrifice His only Son on the Cross.
Abraham took Isaac up in the mountain and tied him down on the altar. As he prepared to kill Isaac, he was commanded to stop and was told that it was only a test of his love for God. From that moment on, Isaac was renamed Israel.
Jews exhibit the same traits both good and bad as any other human line. But non Jewish Christians should treat each Jew with a special nod that they carry a piece, even a very small piece, of Abraham, the line that brought forth Jesus. Jews should be treated with honor because of Abraham.