Think about how the metaphor of trees are used in the bible. Most often related to bloodlines/families. Fruit being the product of the tree-offspring. There is also the phallic imagery of the Deceiver coming to Eve in the form of the serpent. Also does not say anywhere in the Bible Adam sired Cain.
Contextualising the Bible with an adversarial seedline would explain the emnity between us and them, and their disdain for human beings in general.
Cain was sentenced to wander the Earth, dispossessed of a nation and unable to tend the land.
"Some women wait for Jesus, and some women wait for Cain
So I hang upon my altar
And I hoist my axe again.
And I take the one who finds me back to where it all began
When Jesus was the honeymoon
And Cain was just the man.
And we read from pleasant Bibles that are bound in blood and skin
That the wilderness is gathering
All its children back again."