In chapter 3, verses 14 to 19, God lays out His first curses.
14 So the LORD God said to the serpent:So, to sum up, the serpent is forever cursed, losing limbs, perhaps, but certainly eating dirt and nipping at heels for the rest of its existence. This had to have been meant figuratively, in an "eat my dust" sense, because we know that snakes eat small animals, not dirt. Moreover, the curse was not all that effective. Snakes still kill people. If God really wanted to curse snakes more than any beast of the field, He should have pulled out the poison fangs.
"Because you have done this,
You are cursed more than all cattle,
And more than every beast of the field;
On your belly you shall go,
And you shall eat dust
All the days of your life.
15 And I will put enmity
Between you and the woman,
And between your seed and her Seed;
He shall bruise your head,
And you shall bruise His heel."
16 To the woman He said:
"I will greatly multiply your sorrow and your conception;
In pain you shall bring forth children;
Your desire shall be for your husband,
And he shall rule over you."
17 Then to Adam He said, "Because you have heeded the voice of your wife, and have eaten from the tree of which I commanded you, saying, "You shall not eat of it':
"Cursed is the ground for your sake;
In toil you shall eat of it
All the days of your life.
18 Both thorns and thistles it shall bring forth for you,
And you shall eat the herb of the field.
19 In the sweat of your face you shall eat bread
Till you return to the ground,
For out of it you were taken;
For dust you are, And to dust you shall return."
For Eve and every other woman descended from her, God imposes painful childbirth and inferiority to men. This is God's first unjust act. Punishment should be meted out upon the guilty. Why am I punished for the sins of my ancestors? I could be perfect (I'm not, but theoretically, I could be), but apparently, I would still be cursed because of some error in judgment made by someone 100 generations ago. That is unjust.
Adam's punishment is even worse. God curses the very ground of the Earth. He messes up agriculture and grazing, not just for Adam, but all the animals, too, adding thorns and thistles to the landscape.
Justice would have demanded that God carry out the original sentence. Adam and Eve die. Then God can form a new man out of the dust, breathe life into his nostrils, and warn him: "Don't eat the fruit of the tree of knowledge or you will die. I killed the last guy who tried it. See the dead guy in the pit? That's you if you disobey."
Upon further reflection, God is all-knowing and all powerful. Why did He not just make man so that the fruit of that tree would not appeal to him? Give man a sense that is repulsed by the fruit, so he will naturally not even consider eating it? Make the fruit stink like a durian? Make it invisible? Something. Anything. Why waste the glorious creation from chapter one just because man was made so vulnerable to a serpent's temptation?