In the Old Covenant God still instructed Jews to allow outsiders to join. Look at Rahab the Harlot when the Walls of Jericho fell. She became a Jew by conversion.You yourself admit that God never changes. Why would He, He is perfect! But yet, you are arguing that He loves everyone and wishes that all would repent. If that were so, there would be no need for punishment of any kind!
Go back to the OC where He proclaims “Esau I hated”. He stated this prior to his birth. Why then could the same not be true today, in the NC? He does not love everyone, He loves the people of His choosing.
Man, when he reads that story must wonder why He chose Jacob. He was a real scoundrel. He took both his brother's birthright and his blessing. Perhaps it is to teach us that all things belong to Him. Jeremiah 18:5-6
God only knows the answer to this question.
Look at Ruth and Naomi. She became the grandmother of king David whose lineage Jesus chose to come from.
So nothing changed about what you are trying to say because God still aloud sinners to convert back then like He does today in the New Covenant.