We are created in the image of God, as His representatives and messengers. We live in imitation of Him. This can mean many things, and I believe sometimes, we get too much of this wrong, but chiefly, the way in which we image God the most, in my opinion, is as creators. The first commandment to Adam and Eve was to reproduce after their kind, that is, create!
The Sabbath of God was a time in which God could, as it were, reflect and enjoy the goodness of all that He had made. Think of it: He knew it was all going to come down soon enough. The serpent, the tree of the knowledge of good and evil, Eve's deception, Adam's transgression, and thousands of years until the Christ would undo all the undoing of creation.
God resting then, I think, in a manner of speaking, was time taken, as it were, to enjoy the good times, the pure times, the times when all was right with the world and not a single thing was amiss. After
Genesis 3, it's not until
Revelation 20-21 that all that went wrong gets fixed. How many millennia is that? Who knows for sure.
So, why are we given the Sabbath? As imagers of God, we are creators like Him. We have time enough each week to survey all we have, by His good grace, created, that is, our personal world, our family, our home, our church, our neighborhood, and enjoy it for all it is worth. Because all of it entropies in time. Life doesn't stay great forever. Hurts, pains, sorrows, and losses all come. Tears will be, if not constant, at least consistent.
If you and your family have been able to, by God's good grace, create a good life out of this fallen and ready to pass away world, then take the time you have been given, and cease from your works long enough to really appreciate how wonderful and amazing it is that you've got something good going when the rest of the world lives in hell 24/7.
There's your reason to remember the Sabbath and keep it holy. Life is too fast, and it passes in blinks of the eye. Set apart the necessary time, week by week, to memorialize it and sanctify it in your hearts, so you can slow life down and really become present in the moment. Our lives are a vapor, our days are like smoke. Sabbath is the means whereby we construct something solid, temporary as the case may be until our mortality puts on immortality, and so, that which is temporary becomes eternally permanent.
Enjoying Sabbath now prepares us for the forever rest we are going to experience then.