You ignore all of history. The Jews all over the world still honor the Sabbath Day on Saturday. I need no other proof than that. With that the argument should be a shut and closed case. It was given to the Jews and their generations forever. They still keep it. They keep it on Saturday, the seventh day of the week. Case closed.
As you aware the Jewish calendar is a development far beyond the Biblical Calendar given to them by God in the Penteteuch. In the books of Moses God uses numbers not names for the year, month and day. God originates the Jewish religious calendar in Exodus 12:2 and its feasts and Sabbaths in Leviticus 23,25 that form the Biblical calendar.
In this Biblical calendar the lunar 30 day month is followed which is not divisable by seven. However, the seventh day Sabbath is established in this calendar (7th, 14th, 21th, 28th). Hence, the Jewish application of the Seventh day "of the week" Sabbath is Biblical and legitimate.
The Jews went beyond the Biblical calendar and took in the Caananite names for the months and later the Babylonian names for the days of the month and then restricted the Sabbath to the seventh day "of the week" or on Saturday when in fact the Biblical calendar made no such restriction. Indeed, the Biblical calendar allows for the consistent application of the Sabbath law to the 1st, 8th, 15th and 22nd days in every single one of the Calendar Feasts. According to the same development that would establish Sunday as a consistent Sabbath day in the same Biblical calendar. Hence, allowance for the Seventh day of the week Sabbath is Biblical based but restricting it to the seventh day of the week is not Biblical based according to the Biblical calendar given to them by God. Hence, the Jewish model today is a result of the mixture of Biblical calendar, Canaanite and Babylonian ingredients along with TRADITION that goes beyond the Biblical calendar.
The First day "of the week" has as much if not more Biblical basis in the Biblical calendar than does the seventh day "of the week" as the first day of the week characterizes all the feasts of the Jewish religious calendar far more than the seventh day "of the week" Sabbath.
Here is my point - the Jews are correct in recognizing the seventh day of the week Saturday as a legitmate Sabbath day but they are incorrect in restricting it to such. Furthermore, every feast of the Biblical Calendar is a TYPE of the New Covenant and YOU KNOW IT to be true! The seventh day of the week characterizes the OLD COVENANT but the first day of the week Sabbath characterizes every type of the New Covenant within the Biblical calendar as given in Leviticus 23, 25.
We are no longer under the Seventh day of the week Sabbatical cycles (day, month, year) that is the sign of the OLD COVENANT and the nation of Israel. We are under the liberating and blessing of the first day of the week Sabbath that is the sign of the New Covenant both in the pre-cross scriptures and the post-cross scriptures.