Cain dealt with crops,and Abel dealt with animals,plain and simple,and I doubt that they were great merchant men seeing they appear to be the first 2 children of Adam and Eve.
Animal sacrifices,blood,were necessary for the remission of sins in the Old Testament.
Abel sacrificed an animal,good to go,Cain sacrificed,or gave an offering of plant life,not good to go.
Gen 3:7 And the eyes of them both were opened, and they knew that they were naked; and they sewed fig leaves together, and made themselves aprons.
Adam and Eve sinned,covered up their sin with fig leaves making themselves aprons,people's first attempt at religion that does not measure up to God's standard.
Gen 3:21 Unto Adam also and to his wife did the LORD God make coats of skins, and clothed them.
God said not so concerning the fig leaves apron,and made the first animal sacrifice,and fully clothed them.
The story of Cain has nothing to do with prostitutes,or he was a great merchant,for I doubt there were people abroad in great number,and structured to be doing business with them.
But when Cain went off when he received a mark he did build a city there and started populating.
Gen 3:20 And Adam called his wife's name Eve; because she was the mother of all living.
Eve is the mother of all living which means all people came after Eve,so there could not be lost civilizations,and people abroad on the face of the planet,and it would have to be their children that would have to start nations,and civilizations after Adam and Eve,not before them.
And since it appears that Cain and Abel were the first 2 then what lost civilizations,and even if they were not the first 2 children,nobody was before Adam and Eve.
Gen 11:1 And the whole earth was of one language, and of one speech.
Gen 11:2 And it came to pass, as they journeyed from the east, that they found a plain in the land of Shinar; and they dwelt there.
Gen 11:3 And they said one to another, Go to, let us make brick, and burn them throughly. And they had brick for stone, and slime had they for morter.
Gen 11:4 And they said, Go to, let us build us a city and a tower, whose top may reach unto heaven; and let us make us a name, lest we be scattered abroad upon the face of the whole earth.
Gen 11:5 And the LORD came down to see the city and the tower, which the children of men builded.
Gen 11:6 And the LORD said, Behold, the people is one, and they have all one language; and this they begin to do: and now nothing will be restrained from them, which they have imagined to do.
Gen 11:7 Go to, let us go down, and there confound their language, that they may not understand one another's speech.
Gen 11:8 So the LORD scattered them abroad from thence upon the face of all the earth: and they left off to build the city.
Gen 11:9 Therefore is the name of it called Babel; because the LORD did there confound the language of all the earth: and from thence did the LORD scatter them abroad upon the face of all the earth.
It appears that the world was together as one at the tower of Babel,and after that then they were scattered abroad and became different nations,and civilizations,to be able to do business with them.
I believe it is literal when the Bible says Cain dealt with crops,and Abel with animals,and if Cain would of sacrificed an animal it would of been alright.
So the moral of the story in the Old Testament is do not let your job interfere with how you sacrifice,and bring an offering to the LORD.
If you deal in crops do not bring a bushel of apples,and a dozen corn ears.
And if you are a cement worker,mason,do not bring a bag of cement,and a dozen bricks,lol.
Cain specialized in crops so part of his punishment was what he was good at would not increase for him.
So they had to sweat by their brow to provide their food,but Cain had to sweat by his brow,feet,underarms,back,his whole body dripping with sweat like Niagara Falls,yet the ground would not yield her strength,lol again.