I have a germ of idea. What if God’s preference for Abel also introduced the dynamic of God choosing one person over another, as well as the situational superiority of lamb over produce? I know there is symbology/typology with lamb, but it seems things later evened out somewhat when Communion consisted of bread and grapes.
The Fall introduced division among created things as as well as between God and man. Instead of “they”, it became “you” and “not him”. Pride wants us to make it all about me, so when preference is given to someone else, it can be hard to take. So hard, people can resort to murder. I think maybe “we” is easier, but to be the preferred one is better. This is also why Lucifer fell.
Sharing or giving glory is hard for many. I won’t say all. Why do we feel so entitled? There is probably a redeemable function. Reward is a good motivator, but it can too easily become a pathological need. Some are too susceptible to being captivated by its allure. It is sad when temptation is so strong that potentially good things are best avoided.
Humility attracts grace. What if Cain had said, “Good for you, Abel. I can see why God chose your offering over mine.” His inability to do that probably had something to do with his choice of sacrifice anyway.
But what of those to whom the right thing does not come naturally? Those who want the wrong things and when they are discovered, are surprised and angry by the disapproval? James Dean expressed this so well in “East of Eden”. I don’t remember how it ends, but still, it is hard to be content with less favorable attention than seems deserved, flawed perceivers of our own merits and just deserts though we are.