Monotheism is foundational, God exists prior to creation. In the beginning of creation God already is.
In the beginning, God created the heavens and the earth. (Genesis 1:1)Monogamy is seen in the creation of the woman from the man and their joining in marriage. God created both, and intended monogamy in the pre-Fall world.
Then the LORD God said, "It is not good that the man should be alone; I will make him a helper fit for him."Reason is a significant component of the imago Dei. It is a characteristic that we share with God and not the animals. A characteristic we are to use to his glory.
Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh. (Genesis 2:18,24)
Then God said, "Let us make man in our image, after our likeness. (Genesis 1:26)And liberty was given men so they have the capacity to love. Freedom of thought and action was important enough that God ran the risk men would abuse it. We are not given liberty to do as we will, rather that we may submit to God—freely.
And the LORD God commanded the man, saying, "You may surely eat of every tree of the garden, but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die."(Genesis 2:16-17)