There is good reason to believe the ones Peter preached to were of the Essene/Zadok priesthood variety Jews. Your faulty reasoning presents God as changing His mind, as if He cannot see the end from the beginning. Your arguments also sounds like a Catholic assertion or Lutheran. Have you ever stopped to consider the pre incarnation rituals the Jews practiced from time of Moses, which show that belief in Messiah is what God accepts for His Grace to be activated?
Jews came from all over to be at Pentecost in Jerusalem in Acts 2 and Peter condemned them all for crucifying the Christ. Peter commanded them in the plural ‘you all repent’, all Jews as a nation were to repent and each one baptized. If the nation repented then that means each individual Jew was to repent.
Paul makes it plain the Jews were cast off Romans 9-11. God never changed His mind about the Jews for God never promised the Jew unconditional salvation. For though the Jews were chosen in one sense to being the people by which the Messiah entered the world, they still had to obey God to be saved and they would not, Matt 23:37.