The OT is pretty interesting in showing how a people evolved over time. Bigamy was discontinued in OT times. Experience showed it was a bad idea, in addition to being contrary to God’s law. To me, the OT is like the family photo album. You see how people grow and change over time. The toddler pics are true and believable. You do not throw them away. You hang onto the foundational principles— the toddler and the rules he lived by are useful to remember and learn from.
“Bigamy was discontinued in OT times.”
No, it wasn’t. These days it’s merely fashionable to have one legal relationship at a time but there’s no limit on how many legal relationships you have over time.
And it’s not entirely illegal to have adulterous relationships with mistresses (concubines) or a series of consensual one night stands.
Bigamy may have changed but it never went away.
The thing is that these days a man can have a wife and three mistresses and no one cares. But if he commits and calls all four women his wives then people lose their minds and call the police. The relationships don’t change here, just the words or labels we have for them.