It has to do with God’s requirement for sacrifice ... eventually pointing the way to Jesus as the Messiah of Israel, as the sacrifice for each person, individually.
When the first judgement came down, in the Garden of Eden, God showed Adam and Eve, that in order for them to continue living (in their sin condition) that something had to DIE (being the sacrifice for them to continue). And that FIRST SACRIFICE EVER in the history of mankind was God killing an animal (or animals) in order to clothe Adam and Eve. You’ll notice that it was God Himself who set the example for that first sacrifice.
It wasn’t fig leaves that God used, but an animal sacrifice for Adam and Eve.
And this SAME EXAMPLE is carried on throughout all of Scripture, until we get to the ONE AND FINAL SACRIFICE, which is Jesus, the Messiah of Israel.
SO ... with that example, Able “did right” and Cain “did wrong”. Cain did NOT OFFER the sacrifice that was the ENTIRE MESSAGE leading to the ultimate sacrifice. Without BLOOD, there is NO SACRIFICE. That’s why God talks about the “blood of Christ”.
Cain DISOBEYED and did not do right. That’s why God said to Cain ...
4 But Abel brought fat portions from some of the firstborn of his flock. The LORD looked with favor on Abel and his offering,
5 but on Cain and his offering he did not look with favor. So Cain was very angry, and his face was downcast.
6 Then the LORD said to Cain, “Why are you angry? Why is your face downcast?
7 If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it.”
Genesis 4:4-7
God said ... to Cain ... “If you do what is RIGHT, will you not be accepted? But if you do NOT DO WHAT IS RIGHT, sin is crouching at your door ... “
AND SO ... “doing right” is doing it God’s way, as He commanded. And, “doing wrong” is doing it “your way” which is something that God did NOT tell you to do.
And in this example, “doing it right” is offering the sacrifice that God commanded, showing that for is to “continue living” in our sin condition requires something else to DIE and give up its “own life” - which is “in the blood”. And then this leads to the fact that the ONLY WAY TO SALVATION -a is GOD’s WAY which is the “blood of Christ” (”his life) and DYING ... in order that YOU CAN LIVE.
The beginning of Genesis leads us to the very end, which is Salvation in Christ through His shed blood!
Correct on all counts.