The Sabbath is typological of the rest found in Christ. So was the Promised Land.
If a person wants to observe it, fine..but too many of them claim that non-observers aren't even Christians. Why? Because they claim that the Sabbath is a continual, binding commandment, and those who don't observe it are in sin.
Concerning the Roman Catholic Church, Rome was only one bishopric of several. The view of church history that cultists have is defective. Somehow they think that Rome made the decision to "cancel the Sabbath". It is true that in the late fourth century the Church anathematized Judaizers who were causing trouble in the Church, but long before this, the vast majority of Christians had ceased to observe the Sabbath...in fact by the early second century. Even the SDA scholar Samuele Bacchiocchi admits this...therefore he denied the vision that the SDA leader Ellen G. White had, claiming that the Pope changed the Sabbath. The Pope didn't even exist by that time..there was a bishop of Rome but he had nothing to do with it.
Regarding whether the Sabbath will be observed in the future, there are two views of that....I would associate one with dispensationalism, and they claim that Jews will reinstitute the Mosaic Law and will be observing it. The other camp views the words of the Prophets regarding this as typological of obedience to God. In their view, the Jews during the Millennium will not be keeping the Sabbath but observing the Sabbath is communicating to the Israelites that in the future all will be obeying God in all things.
My position is that the Sabbath belongs to the old order..it pointed to Jesus. Jesus was resurrected on the first day of the week as a new creation. Believers are joined with Jesus, and are also the firstfruits of the new creation. We meet on Sunday to commemorate the resurrection, and the fact that we belong to the new creation, and not the old order.
Regarding your claims, Jesus said that the Sabbath was created for man....there is no evidence that it was created in the creation week. It says that God rested on the seventh day. There is no evidence that any man before Moses' time rested on the Sabbath, so it is reasonable that it is part of the Mosaic Law. There were other commandments God gave to men before Moses, but the Sabbath was not one of them.
So, the next claim would be, the apostles observed the Sabbath, and so did the Gentiles. Firstly, the apostles were Jews and they continued to observe festivals and even some purification ceremony (Acts 21). Secondly, Paul used the Sabbath to reach out to people because there were a number of Jews and Gentile God-fearers who attend Synagogue. It was the day of their customary meeting, so he used it.
It is likely that Paul met with Christians on other days (perhaps Sunday) to observe Christian communion and to discuss the Christian message. It is also likely that many other Gentiles joined these meetings.
By the way, I am a former Sabbathkeeper associated with the Armstrongite cult called Worldwide Church of God. So, for over a decade, I held a Sabbathkeeper position. In fact I denied the salvation of any non-observer. So, I know the mentality and have rejected it.