PeterK,
In simple terms, there is this thought also – whenever someone is kind to you in your need, there is a recognition “empathy?” that you would like to reciprocate. Love, in only one direction is admiration.
Now, there are false and true ways to reciprocate love – but even without respect to the “beginning”, a philosophical person can realize that there is a God, and that from this God the whole universe came. So to that person, they would like to give thanks – because humanly it is part of who we are to love those who have loved us in some way.
In this sense, the original idea of sacrifice may have been little more than desperation for the hard times when the crops didn’t grow, or other issues (after all, in the sweat of the brow, not with ease did it grow for Adam). These times reminded the characters in the story about the dependence on whomever made the universe.
But then, how can you “feed” God? – and does not scripture say later that God himself laughs at the notion “Sacrifice and Burnt offering you desired not” that Israel could “feed” him?
But whether mistaken in some measure or not – God chose to accept the Sacrifice of Abel, which is surprising. Sometimes people do try loosely thought out things ( My kids tried playing a grilled cheese sandwich in the VCR! ) – After all where is God, in the earth – or in the sky? and if invisible, then what would his invisible food look like? ( hint: burning makes things disappear. )
Anyway, more speculation – about something that is speculative even inside the story.
God bless you.