Abbas jan, we are talking about the Quran, the WORD of god. There is NO progression. It is ABSOLUTE knowledge coming from him. It's like saying God made a mistake in the bible, but was getting it right in the Quran. God doesn't make mistakes apparently, is all knowing and powerful...yet we have to make concessions here? It makes no sense.
Well done dear, that's good reasoning! I understand that you are engaged in multi-directional debate and do not mean to distract you, but if you wish, there could also be another perhaps simpler explanation. You are correct that your reasoning breaks apart the arguments that portray the Word of God as absolute. It simply is not. In fact all truths in existence are relative and our understanding of them progressive.
God's education, as in human education, comes in progression and in accordance with our comprehension and challenges. A baby is taught how to sit, then crawl, walk, run, run a marathon, play complex sports in steps, so is humanity in general. As we go through school, we continue to gain a deeper knowledge into science, literature and life in general. Life has an evolutionary nature which is hard to deny, but evolution need not contradict previous learning, but complement it. In fact, humans are the only species that are capable of transferring their knowledge and learning through generations which is why we have evolved so much in comparison to say honey bees which have been living the same way, based on same instincts for a billion years.
To perceive any message of God to be His last and final, is in contradiction to His attributes such as All-knowing, All-wise,etc. How can all knowledge be transmitted in one message, as potent as it may have been? This is contradiction in terms. Other than God's own essence which is the only absolute entity, all truths are relative and evolutionary. This is evident in science as well. For instance until recently the existence of ether was widely accepted, but now has been rejected; apes were widely perceived as humans' ancestors, now it is being rejected. Science too is relative and the only undeniable truth about it, in fact about all things including religious truths, is that nothing is the undeniable truth; for our understanding and comprehension of them is in a state of flux and evolution.
Once we recognize the relativity of all truths, accepting past divine revelations, and scientific discoveries for what they were and in the context of their time and challenges becomes more reasonable. For instance, what benefit would it have been for humanity to know that earth was 4.5 billions years old at the time of Christ or Muhammad? They had much more immediate challenges. By your admission science did not even exist in the form that it does today. In time we may discover that their allusions to complex questions that have busied humanity forever, were also not wrong, were not simplistic, rather adequate for the people and challenges of the time.
Therefore one must judge each revelation of the Cause of God in the context and challenges of its own time. God tells us as much as we bear to hear, He teaches us as much as we can learn. His teaching is progressive, ongoing and never-ending. We should not be quick to dismiss the bygone times as primitive and crude, for our own shortcomings will seem primitive and crude for posterity. Instead, we should take comfort that we have been able to benefit from the learning of the past, hopefully make not the same mistakes, and strive to bequeath posterity with a learning which is valuable and worthy of these illumined days.
I applaud your inquisitive mind and critical thinking which will no doubt guide you through your life.