Excellent remark George!
For this discussion it is important to keep in mind the following
It is biologically impossible to establish when the species Homo sapiens or any other species begins with anything other than arbitrary criteria.
Accordingly one has to conclude that Humanity or Humankind begins at the moment when God makes the first creature in His Image.
God makes this at a moment when evolution through “natural deletion of intermediate varieties” has produced a big gap between the kind of body He transforms into the first Image Bearer and all other extant kinds of bodies. This is the moment referred to in Genesis 1:27; 5:1-2; 9:5-6.
So this moment defines the body which is the observable basis or sign in order creatures with capability of freely loving God and accountable for their deeds can ascertain which creatures do share the dignity of Image Bearers and live according to the “Golden Rule”.
Thereby God and the first Image Bearers define the other extant species according to Genesis 2:19-20. Strictly speaking before this moment the concept of species is necessarily fuzzy and arbitrary.
All this means that from Genesis 1 one can infer the following
Each creature aware of his/her accountability toward God’s Law has to respect any creature sharing a human body as Image Bearer.
So we are led to
Does this imply that at this moment ALL creatures sharing a body like that of the first Image Bearers are endowed by God with capability of freely loving Him and thereby accountable for sinning?
In my view the answer to this Question Q1 is NO, for the following reason:
If this had been the case God would have proclaimed at this moment the universal prohibition of “shedding human blood” as He does in Genesis 9:5-6.
The fact that this proclamation happens first at the end of the Flood means that before this moment Principle 2 certainly holds for those who are aware of being Image Bearers, but not for creatures that (although sharing a body like that of Image Bearers) are not accountable for their deeds and therefore do not sin even if they kill each other (similarly as lions did and do).
And now one can further ask
For which reason did God await till the end of the Flood to make “each human being accountable for the life of another human being”?
My answer is: God’s MERCY.
The state of generalized corruption and violence described in Genesis 6:11-13 as cause of the Flood reveals a situation where sinners had lost any awareness to be on earth by God’s mercy, as opportunity to atone. In such situation, for the sake of Redemption, God had to make it clear that He could very well remove sinners from earth at any time and let here only righteous people. This is from God’s perspective the reason of the Flood. So to limit the number of sinners who had to perish in the Flood God awaited the end of the Flood to make each human being accountable for his/her crimes.
The Flood is God’s clear demonstration of His redemptive will: He lets sinners on earth in order they have opportunity to atone.
And the fact that God awaits the end of the Flood for making all people exhibiting a human body accountable for their crimes, is a further demonstration that He “doesn’t take any pleasure in the death of the wicked” (Ezekiel 18:23).