Genesis 1 is a creation of human beings.
If by that you mean that the book of Genesis is NOT divinely inspired and a creation of human beings, you are siding with the unbelieving Higher Critics and apostates. Chapter 1 does not stand alone. The entire book is one unit. You can either accept it as the Word of God, or reject the entire Bible. There's no middle ground.
But since the Lord Jesus Christ confirmed the validity of the Genesis account, then you should abandon that false belief. Genesis 1 (and following) is a revelation from God, since only God was present at creation. And it is BY FAITH that we understand that the worlds were framed by the Word of God.
So what do we learn from the Creation Account (which is solidly confirmed in the Ten Commandments, which were written with the finger of God):
1. The entire universe was created in six literal 24 hour days OUT OF NOTHING.
2. (a) all living creatures on land, (b) Adam, and (c) Eve were all created on the sixth day.
3. Genesis 2 expands the narrative regarding the creation of man and woman as well as the creation of the Garden of Eden.
4. God rested on the seventh day from all His creative works. Therefore He blessed, sanctified, and hallowed the seventh day.
5. This is fully confirmed in the Ten Commandments (Exodus 20:8-11):
8 Remember the sabbath day, to keep it holy. 9 Six days shalt thou labour, and do all thy work: 10 But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: 11 For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
In view of this the earth is no more that approximately 6,000 years old, even though God has given many natural features the appearance of an older age. We should also remember that the Genesis Flood affected the topography of the earth tremendously. See
The Genesis Flood by Whitcomb and Morris.