I wondered if that story was supposed to show the Jewish God's distinction from false idols that do demand human sacrifice, carried through. Essentially, this God demands faith and obedience, but is also merciful (and is opposed to human-on-human bloodshed, hence the mark of Caine, the post-flood covenant). But I have no knowledge of if such other religions existed at the time.
It could also just be a variation on the 'honor thy father' principle - which after all is an important one for the maintenance of social order (and still presumably figures in many modern stories).
Hopefully going to reume my Bible studies this week, just had a heavy weekend and feeling appropriately guilty. Not read up to Abraham and Isaac.
That's similar to the way that the horrific Levite & Concubine story is "supposed" to be read and it's where theological exegesis can shed light on these otherwise baffling texts.