I think it would be a mistake to interpret the image God created Adam ("mankind") in, as something purely related to resemblance. This possibility is already excluded to a certain extent by the fact that this "man" was created "male and female". I have little doubt that it refers to a particular expression of God's qualities - the
human expression - not an exact "copy" (for instance: God-like autonomous understanding of good and evil; man was not like Him in that regard before the fall) - and it's therefore a stretch to assume that it's particularly a physical resemblance. All verses that point to man's likeness to God refer to virtues like justice (Gen. 9:6), authority (1 Cor. 11:7), knowledge/truth (Colossians 3:10) and respect (James 3:9). Each of these have particular physical expressions, like covering one's head or not (1 Cor. 11:7), but the physical dimension (a woman covering her head) is not derived from the principle (modesty or respect) itself; something else makes it valid, like law, context or culture (it was disgraceful for a woman to have her head shaved).
In the same way, any physical resemblance to God can only be valid as far as God
expressed himself physically, just like our
moral resemblance to God could only be valid as far as He expressed himself verbally - as far as we conformed to his commands. When Adam sinned, he
deviated from God's revealed image, and his resemblance to God became more superficial (he became more like an autonomous moral agent, "like God", but considering his actual dependent status, as a creation of God, this did not mean he became better at being
human). In other words: man had to rely more on a physical existence, complete with toil, suffering and death - separated from paradise - because his spiritual relationship with God had suffered. Even as Adam strived to become more like
God is, he became less like God wanted
him to be - less like the original image he was created in. The simple reason was that our likeness to God did not depend on our effort or will - our physical nature - but on
God's will and nature, on who and what He wants us to be. So God restored his blueprint for us: His only Son, in whose
image we could again be called "sons":
Col. 1:15-21 He is the image of the invisible God, the firstborn over all creation. For by him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things were created by him and for him. He is before all things, and in him all things hold together. And he is the head of the body, the church; he is the beginning and the firstborn from among the dead, so that in everything he might have the supremacy. For God was pleased to have all his fullness dwell in him, and through him to reconcile to himself all things, whether things on earth or things in heaven, by making peace through his blood, shed on the cross.
Once you were alienated from God and were enemies in your minds because of your evil behavior. But now he has reconciled you by Christ's physical body through death to present you holy in his sight, without blemish and free from accusation
And this is how God worked our salvation. He let His image pass through sin and death, so that we could be
like Him when we went through the same - not
unlike him anymore, physically and mentally (note the words "enemies in your minds" and "reconciled ... by Christ's physical body"): "
For what the law was powerless to do in that it was weakened by the sinful nature, God did by sending his own Son in the likeness of sinful man to be a sin offering. And so he condemned sin in sinful man" (Rom. 8:3).
So, God's image is not a carbon copy, a blanket representation of God that we all automatically share in. It is something we must conform to (Rom. 8:29). It is something quite apart from a natural likeness (1 Cor. 15:49). In fact, it's a
spiritual glory (2 Cor. 3:18; see also Psalm 106:20 and Rom. 1:23).
And lastly, there are even images that might seem for all like God. They may seem to come by his authority and even to bear the likeness of his Son (see my commentary in brackets):
Rev. 13:11-15 Then I saw another beast, coming out of the earth [i.e., like Adam]. He had two horns like a lamb, but he spoke like a dragon [its appearance is deceiving]. He exercised all the authority of the first beast on his behalf, and made the earth and its inhabitants worship the first beast [it has an ordained authority], whose fatal wound had been healed [in imitation of Jesus]. And he performed great and miraculous signs, even causing fire to come down from heaven to earth in full view of men. Because of the signs he was given power to do on behalf of the first beast, he deceived the inhabitants of the earth [they were able to justify believing it]. He ordered them to set up an image in honor of the beast who was wounded by the sword and yet lived. He was given power to give breath to the image of the first beast, so that it could speak and cause all who refused to worship the image to be killed.
Revelation goes on to tell us the name (or "number") of this beast:
man. A false image of God is still an image of God... What man considers "likeness" may not be God's likeness at all.