God values humans out of His love for us and that we are created in His image. That value exists outside of human thoughts and desires. Therefore, it exists objectively.
So humans have objective value if, and only if, they are valued by somebody who is not himself human? This seems an entirely arbitrary rule.
First, it doesn't bring us to "human value is an objective fact," it only brings us to "from the subjective perspective of a non-human, humans have value." A definition which would seem much more in line with the typical use of "objective" would be "humans have objective value if that value exists whether or not
anybody believes that value exists."
Second, if somebody's subjective perspective is enough to give "objective" value to somebody else, there seems no reason not to grant that any individual human has objective value if she is valued by other humans. Again, "that's not good enough, it has to be a non-human" just seems to be an arbitrary standard.
Third, this rule must proceed from the more general rule, "any object belonging to Set S has objective value if, and only if, it is valued by somebody who is not a member of Set S." In that case dogs have objective value because humans love them for their loyalty and cuteness; it's a value which exists outside of canine thoughts and desires, therefore it exists objectively. Are you OK with that?
Fourth -- again -- by this definition humans also have objective value if they are valued as an energy source by the machines which run the matrix, in which case our "objective value" is hardly something which is necessary for morality, or even relevant to it. You can have an "objective source of value" which doesn't help you in the slightest to make decisions about morality.
Now if you say "but the aliens are selfish while God is loving," then you're rewriting the definition. Now the definition says "humans have objective value if, and only if, they are valued by somebody who is not himself human
and who does not have self-centered motives." But at that point your definition is even more ad hoc and arbitrary, and -- maybe more crucially -- in that case it isn't clear that God meets that definition. To say that God loves humans because they are made in his image simply makes God a lover of himself, and you've been insisting over and over that you
can't base morality on the "sentimental" liking of yourself and those like you. If, on the other hand, "you are valuable because you are like me"
is a good enough reason to assign value to something, then "humans are valuable because they are like me (a human)" is a good enough reason also.
I think that will do for a start.