This is the iconic story of Cain and Abel.
We need to be clear at the outset. What Cain did was wrong. At all times, from all perspectives, Cain was just wrong. It was murder. It doesn’t matter his reasons or what he felt, it was wrong to decide for himself that his brother should be killed. Full stop.
With that out of the way, lets pick apart the story.
At no point does God indicate his preference for fat portions. At this point in the narrative, God has not declared what type of sacrifice is better. Both Cain and Abel provide from what they can: Cain from the field, Abel from the flock. The first question is why would God prefer dead animal fat to harvest. This is completely arbitrary. Cain and Abel chose their professions, one would assume, out of necessity. On the face of it, meat and vegetable, being both necessary for life, make keeping flocks and working the soil appear as equally valid pursuits.
Yet in Gen 4:4-5 God appears to randomly show favor on Abel’s work and in Gen 4:6-7 appears to bitch Cain out for having a reaction to it. The literal creator of the universe decides you offering is crap and you aren’t supposed to be upset? The same question keeps coming back: If God created these people, how is he so inept at predicting their actions?
Well, Cain goes and kill his brother. God punishes him by making it harder to work the ground (which seems kinda pointless, considering God clearly didn’t want him doing it in the first place). He sent him out into the wild world with a mark (so no one would harm him) and found himself a wife. Wait, wha?
There are a boatload of continuity issues up to now, but this one takes the cake! Up to now, according to the narrative, there are exactly 3 people on the earth. In the whole of the universe, in fact.
Since we are given no context of these events in time, we don’t know how these events fit with other events. Adam and Eve go on to have another son, Seth, to replace Abel. Seth, in this chapter had a son named Enosh. Gen 4:26 mentions other men, who began calling on the name of the Lord. Who are these men and where did they come from?
In the next chapter we hear about other sons and daughters, and the ages of the important ones, but we are left to wonder if these entirely unconnected lines of narrative do in-fact converge.
We hear about the lineage of Cain and the apparent exploit of his descendant, Lamech, in Gen 4:23-24 who tells his wives about killing someone for wounding him. We get some odd “curse math” about Lamech’s vengence being 77 times. Cain’s was 7 times. How does 4 generations get you 77-fold?
I don’t even think they’re trying to be coherent. Yet, if you view it in the light of creation folk-lore, it’s no weirder than all the other ones.