We know everything in this world goes systematically and in planned way either it is from Allah (swt) or we human beings do in our day to day life. For example there was a day we had windows 1998 but now we are using windows 10 so if you ask why computer engineer didn’t make 2010 version in his first attempt.
Of course here you can say Allah does not work like an engineer because Allah knows everything but yes true Allah knows everything since it’s beginning but what about the creation? We do not have the capacity and capability that’s why we need to improve our understanding and capabilities of knowledge. Quran is the final book therefore it must be revealed finally and with a messenger who is also the final messenger.