When Christ returns, then... we all are going to honor God's Sabbaths and holy days, and laws of His House (per Ezekiel 40 - 48). This is also covered in passing in Hebrews 3 & 4 about Christ's future Millennium, a 'day' of His Rest. Until then, the traditional sabbath represents a shadow of the real Sabbath yet to come.
The real sabbath? that day was established in Genesis:02 01-05 before there was a man to til the ground!
This fact is established in the very scripture that you quote, Hebrews 04:04
So let's examine the sabbath which is yet to come:
The bible clearly commanded that man is to rest in the ten commandments, Exodus 20:08.
In Ezekiel 20:19-20 he expounds further on the sabbath that it is a sign of belief: "I [am] the LORD your God; walk in my statutes, and keep my judgments, and do them; And hallow my sabbaths; and they shall be a sign between me and you, that ye may know that I [am] the LORD your God." How is the seventh a sign between man and Christ? Because he rests every seven days just as he commanded us to do the same, that's how. We already covered Jesus resting on the seventh day before he created man, again in Genesis 02:01-05.
Psalms 90:04 & II Peter 03:08 reveal the relative time scale for celestial beings(God, angels) against that of flesh & blood as it reads:
"But beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day."
This scripture places the appearance of Jesus in his kingdom around seven thousand years after the birth of the first man Adam, and it is totally plausible. The reason it plausible is because of whats written in Revelation 20:01-07 where Satan is bound in chains for a millenium day or one thousand years. This is explains why Jesus made the remark to the Pharisees that questioned his disciples plucking and eating corn on the sabbath day in Mark: "the sabbath was made for man, and not man for the sabbath." This is because Jesus does not need rest from Satan, man does! Remember, i
t was Jesus that cast Satan to the earth before he created man from the dust of the ground.
The question now becomes what is the first day(or thousand years in Gods time) and who is it a sign between?
Remember now, when Christ warned Adam & Eve not to eat of the fruit(of lies) from Satan, he gave them the following quote:
Genesis 02:17 - "But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die."
Satan afterward brought death upon all men froward by convincing Adam & Eve to disobeying the Lord's commandment(much like the Sabbath command), and Adam literally died in that same God-cycled millenium day in Genesis 05:05
"And all the days that Adam lived were nine hundred and thirty years: and he died."
Other questions that I have to anyone who believes in the first day being the sabbath day are:
1. Shouldn't the Lord have rested on the first millenium day of creation of the earth, sun, and moon, instead of doing otherwise in Genesis 01:01-05?
2. Shouldn't the Lord have rested on the first millenium day after Genesis 02:02, instead of creating Adam & Eve?
Nothing wrong if a believer on Christ wants to observe Saturday as God's Sabbath, or even Sunday under Christ either (Colossians 2).
Col 2:14-17
14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to His cross;
15 And having spoiled principalities and powers, He made a shew of them openly, triumphing over them in it.
16 Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon,
or of the sabbath days:
17 Which are a shadow of things to come; but the body is of Christ.
(KJV)
The Greek word for "sabbath" there is 'sabbaton', specifically the idea of the weekly sabbath.
Mark 2:25-28
25 And He said unto them, Have ye never read what David did, when he had need, and was an hungred, he, and they that were with him?
26 How he went into the house of God in the days of Abiathar the high priest, and did eat the shewbread, which is not lawful to eat but for the priests, and gave also to them which were with him?
27
And He said unto them, The sabbath was made for man, and not man for the sabbath:
28 Therefore the Son of man is Lord also of the sabbath.
(KJV)
God made the sabbath FOR... man, not man FOR... the sabbath, per our Lord Jesus Christ.