The Sabbath was made for man yes, in that we rest in Him.
Matthew 11:28 Come unto me, all ye that labour and are heavy laden, and I will give you Sabbath.
It is beneficial for all of us to get plenty of rest but it's not a law for us to keep the Sabbath in any way shape or form, it was given to man in the OT to be observed and obeyed and in the New Testament, God gave His Son in whom by trusting in Him we do enter into Sabbath. No longer observing it in our flesh but by faith we have entered into His Sabbath and by that alone is sufficient as far as our part is concerned.
Hebrews 4:3 For WE WHICH HAVE believed do enter into rest,
We have, past tense have entered into His Sabbath.
Though all these things have been done in the Spirit, I do not negate the fact that rest is necessary for the flesh, but it's not a law that one should keep, however, rest will benefit all of creation when we do observe them for the sake of that which requires rest.
For example, It is said that by tilling the soil for six years on the seventh let the soil rest. And there is great benefit when a field is left from being tilled. In this world today, the soil is worked until it's lost it's ph balance. So they put more ph into it trying to work it some more and their crops are not producing properly. The ground needs rest. The same goes for human beings when we push and work and we don't sit down and take time for reflexion we put the body under such stress that we have anxiety attacks and we wonder why we have pressure in and around our heart. We sleep for six hours per night and wonder why ten cups of coffee isn't working anymore. The ph we are adding is not working, we need the rest.
This type of rest and Christ rest is not the same thing. One is wrought by faith, the other is just common sense. We know that if we overwork something it's going to break down. But the rest that is in Christ, there is no labour in trying to obtain favour with God, we have that by faith in Christs' work. Since Christ obtained our righteousness by His work, our rest is obtained by faith and has nothing to do with whether I keep Saturday or Sunday or any day of the week. Or whether I let my fields rest or not, that does not change our sabbath in Christ.
However, letting our fields rest is still a good idea. Getting eight or more hours of sleep per night is also a good idea. This type of rest has nothing to do with our standing in Christ Jesus.