It seems quite plausible that Adam would have been given an awareness of the significance of every 7th day as a "Day of Rest" and also both Abel and Cain that a "Day of Rest" was made for man from the
Get Go. It may have been every 7th Day that the
LORD walked in the cool of the day at the time of the evening breeze with Adam and his wife. Then again this awareness of the "7th Day of Rest" became even more meaningful after they left the Garden of Eden having to work by the sweat of their brow until they returned to the ground;
"for dust you are and to dust you will return" (Genesis 3:19).
Is it not possible that Abel honored the 7th Day of Rest unto the Almighty Creator; while Cain was half-hearted in his observance. And in time, it was the nature of fallen mankind to dishonor the 7th Day of Rest to the extent that ...
Bereshit 6:5-8 (Chabad Tanach ~ CJB ~ doesn't use all CAPS for YHVH)
5 And the Lord saw that the evil of man was great in the earth, and every imagination of his heart was only evil all the time. הוַיַּ֣רְא יְהֹוָ֔ה כִּ֥י רַבָּ֛ה רָעַ֥ת הָֽאָדָ֖ם בָּאָ֑רֶץ וְכָל־יֵ֨צֶר֙ מַחְשְׁבֹ֣ת לִבּ֔וֹ רַ֥ק רַ֖ע כָּל־הַיּֽוֹם:
6 And the Lord regretted that He had made man upon the earth, and He became grieved in His heart. ווַיִּנָּ֣חֶם יְהֹוָ֔ה כִּֽי־עָשָׂ֥ה אֶת־הָֽאָדָ֖ם בָּאָ֑רֶץ וַיִּתְעַצֵּ֖ב אֶל־לִבּֽוֹ:
7 And the Lord said, "I will blot out man, whom I created, from upon the face of the earth, from man to cattle to creeping thing, to the fowl of the heavens, for I regret that I made them." זוַיֹּ֣אמֶר יְהֹוָ֗ה אֶמְחֶ֨ה אֶת־הָֽאָדָ֤ם אֲשֶׁר־בָּרָ֨אתִי֙ מֵעַל֨ פְּנֵ֣י הָֽאֲדָמָ֔ה מֵֽאָדָם֙ עַד־בְּהֵמָ֔ה עַד־רֶ֖מֶשׂ וְעַד־ע֣וֹף הַשָּׁמָ֑יִם כִּ֥י נִחַ֖מְתִּי כִּ֥י עֲשִׂיתִֽם:
8 But Noah found favor in the eyes of the Lord. חוְנֹ֕חַ מָ֥צָא חֵ֖ן בְּעֵינֵ֥י יְהֹוָֽה:
Perhaps one reason Noah found favor in the eyes of the
LORD is that he and his family rested every 7th Day before and during the building of the Ark. Even though due to mankind's evil tendencies they still may have had some awareness of a 7th Day of Rest (according to the then reckoning of time), but they no longer observed it unto the
LORD, but instead wasted the day in wanton pleasure.