I'm still trying to grasp the way of transmission of the Torah knowledge from day 1. This question can equally deal with two phenomena: the commandment of eating the forbidden fruit or the commandment of the 7 Laws.
IIRC (please correct me if I'm mistaken):
- G-d creates Adam
- G-d commands Adam not to eat the fruit and (independently) keep the 7 Laws
- It is clear that G-d expects all humans to observe the commandments given to Adam.
G-d doesn't command Adam to pass it on to other humans, his wife or sons or descendants.
G-d harshly judges Eve and Adam's descendants for not keeping the commandments.
The necessity of passing the commandments is absolutely crucial for the justification of G-d's judgment both for Eve eating the fruit or Kain killing Abel.
This is true for all following generations that could claim that though Adam was commanded, he didn't bother teaching the future generations, just as he didn't bother to teach his own wife.
Why didn't G-d care to command Adam (and following generations) on passing the original Law on?