I agree with you about Saturday being the day to keep holy. Great analysis.
For instance, Jesus died for our sins on a Friday. That is arguably the most significant event in all of history,
I deny both of these. I hold the greatest event in human history was God raising Jesus from the dead into a glorified body. Everyone dies. The resurrection is our proof of what Jesus died for.
Also, I hold Jesus died on Wednesday - because Math, coupled with Scripture saying he was in the ground for 3 whole days, as Jonah was in the belly.
- t = 0, Wednesday @ Dusk Jesus is put in ground. Preparation Day, beginning at sunset. Special Sabbath.
- t = 1, Thursday @ Dusk. Passover, beginning at sunset. Special Sabbath.
- t = 2, Friday @ Dusk.
- t = 3 days, Saturday @ Dusk. Regular Sabbath ends at sunset.
It is true that Jesus was raised on the first day of the week, Sunday.
Some read the Bible and conclude Mary missed the greatest event in human history by moments. The above shows she missed it by ~ 12 hours. The Jewish day begins at sunset, as dusk ends.
We keep holy the Sabbath day to commemorate when God rested after Creation, on the 7th day. Again, the Hebrew day begins at sunset. The 7th day begins at sunset on Saturday. Remarkable symmetry to the math above.
The literary parallelism between God's creation and Jesus' resurrection, the beginning of a new creation reconciled to God through Christ, is to awesome to disregard. A Sunday resurrection has no historic parallel, and as you pointed out, no Scripture to support we ought to keep it holy.
The first day is a day to be productive, not to rest. Are we that lazy? Start off resting? Common on now!