Genesis doesn't call the sun day, He calls it a marker to indicate days. He calls the light 'day', and the darkness 'night'.
But the passages state 'there was evening, there was morning- the x day'
It does not say there was night, there was day.
So the passages themselves show that evening and morning are not dependent on the sun and moon, but rather God made the sun and moon to be dependent on what He considers a morning and evening.
But it's not so black and white:
The moon is not always there. In an event of a new moon, it is the absence of the sun that makes it night. And since we see the moon sometimes during the day, it all amounts to one conclusion- they govern and separate, but they are not personas of night and day themselves. They are indicators and work together to mark the calender. The sun is constant, and the moon phases.
It's a system, indications, to let us be aware of evenings and mornings, so that even when we are at the North Pole during it's time of darkness, we know when day will eventually approach.
I'm going to go on ignoring the stuff you say about the moon, but I want you to know it is not out of any kind of disrespect. I have never, and do not intend to, discuss the moon as any kind of factor in this. Therefore, I simply have nothing to discuss about that. Just to let you know.
As far as your other comments, I would say this in relation to the OP:
The argument is often presented that today we understand the universe in a certain way, and we believe it is consistent in its operations, and has been since the beginning. Therefore, we find no problem projecting unto that beginning the same circumstances we encounter today. Therefore, projecting back as we do, we find no fault project onto the first days of Creation that same duration and measurements of time we observe today.
This is not an argument I accept for a number of reasons. First, the object in space that causes the phenomenon we call day, morning and evening (the sun) is not said to exist until the fourth day. Second, the phenomena described in the text are only observed from the ground on Earth, and do not represent a cosmological perspective beyond that of a casual observer, and thus do not suffice as credible on a cosmological level. Third, the argument ignores the history behind the development of our modern ways of measuring time, and assumes we have always measured in the same way throughout the ages. Therefore, I cannot accept the text as evidence that Creation took six 24-hour days as we understand days today.
It is simply speculative that mornings and evenings in an approximately 24-hour cycle would exist without cosmology being just the way it is today, since there is no way to test/prove this. Therefore, there is absolutely no reason to believe the sun and rotation of the Earth just happen to correlate with days rather than actually causing them, as you suggest.