Suppose that God just picked some things and said "um these things are good and these things are bad. " This would appear arbitrary because the thing is not good in itself, It is only good because God said it is good. We would also expect to see some ambiguity where "good" and "bad" intersect. In fact we do. Moral dilemmas are illustrations of such moral ambiguity (see The Trolley Problem). If something is "good" because God willed it, And that claim alone results in ambiguity about whether something is good, Then the resulting paradox is an indication that this is not what makes something "good. "
Elohim/God is the very thing that we call good. There is no need for him to play a guessing game. He went out of his way to show through creation, After every moment of creation he said he saw that it was good not it is good. This indicates that Elohim/God attributes are already in creation and can’t be separate from him. Something that is called “bad” is when humans takes it upon themselves to separate Elohim/God out of their lives. Thank Elohim/God for Yeshua/Jesus of Nazareth for giving us a chance to reunite with him. If you want to experience this all you have to do is confess Yeshua/Jesus is lord, Believe! That Elohim/God raised him form the dead and proved his promises that whoever believes in him will have eternal life!