Then let me ask you how you understand Romans 5:13-14
Rom 5:13 (For until the law sin was in the world: but sin is not imputed when there is no law.
Rom 5:14 Nevertheless death reigned from Adam to Moses, even over them that had not sinned after the similitude of Adam's transgression, who is the figure of him that was to come.
See below:
How did Isaac of Genesis, for example, end up also becoming sin and dying, even when sin was not imputed unto him, because there was no law given?
He didn't become sin. No one can do that. People die the first death because they are mortal. The above verses speak of a spiritual death not a physical death. Physical death did not stop reigning at Moses, which means when the law came. Only spiritual death stopped reigning because of God providing a way to remove sin through the sin sacrifices of animals and the shedding of their blood. It was not a perfect system but it was enough until Christ came.