What has Genesis 2:7 got to do with the seventh day? Genesis 2:7 (WEB):
(7) Yahweh God formed man from the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul.
What it says in Genesis about the seventh day is:
Genesis 2:1-3 (WEB):
(1) The heavens, the earth, and all their vast array were finished.
(2) On the seventh day God finished his work which he had done; and he rested on the seventh day from all his work which he had done.
(3) God blessed the seventh day, and made it holy, because he rested in it from all his work of creation which he had done.
It simply says that God rested on the seventh day; it doesn't say that the seventh day never ended. God started his rest on the seventh day, i.e. He had finished His work on the sixth day, and He continues to rest from His work of creation, but that doesn't mean that the length of a day changed at that time, that there was never an eighth day and that we've all been living in just one day!
Hebrews 3 (WEB):
(11) as I swore in my wrath, ‘They will not enter into my rest.’”
(19) We see that they were not able to enter in because of unbelief.
The rest that Paul is referring to is the rest that God had promised to men if they would obey Him, and in particular to the rest in heaven promised to the Christians he was writing to. Barnes' Notes on Hebrew 3:11 says:
It is called “my rest” here, meaning that it was such rest as God had provided, or such as he enjoyed. The particular “rest” referred to here was that of the land of Canaan, but which was undoubtedly regarded as emblematic of the “rest” in heaven. Into that rest God solemnly said they should never enter. They had been rebellious. All the means of reclaiming them had failed. God had warned and entreated them; he had caused his mercies to pass before them, and had visited them with judgments in vain; and he now declares that for all their rebellion they should be excluded from the promised land. God speaks here in the manner of human beings. Men are affected with feelings of indignation in such circumstances, and God makes use of such language as expresses such feelings. But we are to understand it in a manner consistent with his character, and we are not to suppose that he is affected with the same emotions which agitate the bosoms of people. The meaning is, that he formed and expressed a deliberate and solemn purpose that they should never enter into the promised land. Whether this “rest” refers here to heaven, and whether the meaning is that God would exclude them from that blessed world, will be more appropriately considered in the next chapter. The particular idea is, that they were to be excluded from the promised land, and that they should fall in the wilderness. No one can doubt, also, that their conduct had been such as to show that the great body of them were unfit to enter into heaven.
Barnes' Notes on Hebrew 4:4 ("For he has said this somewhere about the seventh day, “God rested on the seventh day from all his works;”") says:
For he spake - Gen_2:2. “And God did rest.” “At the close of the work of creation he rested. The work was done. “That” was the rest of God. He was happy in the contemplation of his own works; and he instituted that day to be observed as a memorial of “his” resting from his works, and as a “type” of the eternal rest which remained for man.” The idea is this, that the notion of “rest” of some kind runs through all dispensations. It was seen in the finishing of the work of creation; seen in the appointment of the Sabbath; seen in the offer of the promised land, and is seen now in the promise of heaven. All dispensations contemplate “rest,” and there must be such a prospect before man now. When it is said that “God did rest,” of course it does not mean that he was wearied with his toil, but merely that he “ceased” from the stupendous work of creation. He no more put forth creative energy, but calmly contemplated his own works in their beauty and grandeur; Gen_1:31. In carrying forward the great affairs of the universe, he always has been actively employed - John 5:17 [But Jesus answered them, “My Father is still working, so I am working, too.”], but he is not employed in the work of “creation” properly so called. That is done; and the sublime cessation from that constitutes the “rest of God.”
You're believing the theories of men and forcing God's word to fit in with that, rather than believing God. The "community" that guesses at the date of creation of animals and plants, and theorises that they were created millions of years ago, have not been very scientific and they have got it wrong! The more "scientific" evidence, such as the slowing speed of light and our modern uderstanding of genetics, prove those old theories to be wrong.
Exodus 20:9-11 (WEB):
(9) You shall labor six days, and do all your work,
(10) but the seventh day is a Sabbath to Yahweh your God. You shall not do any work in it, you, nor your son, nor your daughter, your male servant, nor your female servant, nor your livestock, nor your stranger who is within your gates;
(11) for in six days Yahweh made heaven and earth, the sea, and all that is in them, and rested the seventh day; therefore Yahweh blessed the Sabbath day, and made it holy.