You aren't being very clear here. Are you saying "the Sabbath was originally the day of God's rest" is wrong?The major flaw in this idea is that the Sabbath was originally the day of God's rest. Therefore Christ (who is the Creator) RESTED on the Sabbath after His crucifixion, and rose again on the "morrow after the Sabbath" to fulfil the Feast of First Fruits. The first day of Creation corresponded to the first day of the New Creation.
What I know is that when I read the Gospels, Jesus "appeared" to the women early the first day of the week. Close to sunrise. It is not called the Lord's Day. It does not say Jesus was resurrected on the first day of the week. You are speculating to justify following the Catholic tradition.