The thing is though, gotime, that the day on which God rested was like none of the others. We read no "and there was evening and morning, a seventh day". It was perpetual blessing that Adam and Eve were created into. This was the result of God's blessing the perpetual Sabbath and Adam and Eve enjoyed this perfect relationship with God until they sinned. It is therefore wrong to say "this day was special because it was made by God to be Holy to be set apart." No day needed to be set apart before sin. It was perpetually day and nothing but blessed.
The first we read about the Sabbath of the commandment, a 24-hour period, is in Exodus 16, shortly before the giving of the law. This sort of thing also happened in the case of the Passover.
There are two reasons for the giving of the commandment to keep the Sabbath day holy. In Exodus 20 it is because God rested and blessed the day and in Deuteronomy 5 the children of Israel are to keep the day to remember their deliverance out of slavery in Egypt.
It therefore foreshadowed the coming of Jesus, who would deliver us from bondage to sin and restore uninterrupted rest and the relationship with God that Adam and Eve had enjoyed in the beginning.
You're right to say "sin is not remembering to keep the Sabbath holy", gotime, but you're focussed on the shadow rather than the reality. Sin is indeed not seeing Jesus, our Sabbath rest, as holy and acknowledging God's provision of a Saviour in him. But there is no sin in not observing the weekly Sabbath or we would certainly be reading about it, under the new covenant, in the New Testament.
What you have said here sounds great and has the appearance of sound reasoning, but you have missed something.
The commandment itself which acts as a reminder stipulates that it was a "day", now There is the possibility that this word can be used to mean a longer time but the context gets rid of that possibility.
The whole point of the commandment which you have missed is that it is a reminder that the 7th day is Holy. as seen here:
Exo 20:10
But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:
The commandment does not say, I make it holy now. It says that it was made Holy at creation:
Exo 20:11 For in six days the LORD made heaven and earth, the sea, and all that in them is,
and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
Where your error seems to be is in your reading of the commandment itself. You seem to think and correct me if I am wrong. But you seem to think the 7th day became Holy at the giving of the commandment or some time close.
But the text is not an establishment but a reminder hence the word "Remember" and the stating at the end of the commandment that it was made Holy on the 7th day of creation.
There is no question here that the 7th day was also considered a day not a period of time ending or unending. You have to ignore the text to come to that.
It is in fact the commandment that solidifies that Creation took 6 literal days not 6 periods of time. It also eliminates the gap theory.
You also call it a shadow clearly ignoring its origin and purpose given by God himself. My original OP deals with this already.
SO with respect I have to disagree with your opinion on this matter. I say opinion because you did not use scripture as I did for my position on this. And the scripture clearly debunks this Idea you have given.