Then nobody should have sinned and disobeyed God at any point - yet they did.
In references to the Sabbath as being set aside for a day of worship was not mentioned until Exodus chapter 16.
In Genesis 2:2-3 it said God bless the seventh day. In between then and Exodus 16 there is no mention of the 7th Day or the keeping of it.
But as with many things in Scripture, where there is no definite analysis men assume.
The Law was understood by all because humanity was made in God's image and likeness. They did not have to be commanded they understood because it was part of them being made in His image and likeness. No assumption, that is what scripture says. The Written Law did not come until Moses. But the things of God, righteous living and holiness was and is part of who we are, being made in His image likeness to walk.
Rom 1:18
For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness;
Rom 1:19
Because that which may be known of God is manifest in them; for God hath shewed it unto them.
Rom 1:20
For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse:
Rom 1:21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
Gen 26:5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
When God put the law in the heart of man would be much later
Bible Gateway passage: Jeremiah 31:33 - King James Version
The following is in the present tense. And there is a good reason why it was paraphrased again in Romans 10:6-8
Deut 30:10 If thou shalt hearken unto the voice of the LORD thy God, to keep his commandments and his statutes which are written in this book of the law, and if thou turn unto the LORD thy God with all thine heart, and with all thy soul.
Deut 30:11 For this commandment which I command thee this day, it is not hidden from thee, neither is it far off.
Deut 30:12 It is not in heaven, that thou shouldest say, Who shall go up for us to heaven, and bring it unto us, that we may hear it, and do it?
Deut 30:13 Neither is it beyond the sea, that thou shouldest say, Who shall go over the sea for us, and bring it unto us, that we may hear it, and do it?
Deut 30:14
But the word is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it.
Thank you for sharing your belief!
If we avoid condescending remarks our conversation will go much better. Thank you.