Why did Muhammad have more wives

My Imam, in our discussions with the Christians about the proofs of the call, we often see them moving to matters concerning the character of the Messenger Muhammad pbuhap. One of their questions is: Why did the Messenger pbuhap have nine wives? Could you please clarify the reason?

6 days of creation

“Say: Is it that ye disbelieve in Him Who created the earth in two Days? And do ye join equals with Him? He is the Lord of (all) the Worlds. He made therein Rawasy (stabilizers) from above and bestowed blessings in it, and gave due measure therein the sustenance, in four Days, for those who question.
And then He established it until to the sky, and it had been (as) smoke: He said to it and to the earth: “Come ye together, willingly or unwillingly.” They said: “We do come (together), in willing obedience.”
“And so He completed them as seven skies in two Days, and He inspired to each sky its command. And We adorned the sky of the world with lamps, and protected it. Such is the Decree of (Him) the Exalted in Might, Full of Knowledge.” [Qu’ran Surat Fussilat (41):9-12]

Why was the period of creating the earth and its sustenance four days, while the creation of the skies was two days since the skies are greater?

How long did Noah live?

As the Homo sapiens human evolved from a lesser species through evolution, with each new generation improving until his brain reached the required volume and capacity, how are the long lives of the early prophets pbut like Noah explained? The Holy Quran says that he pbuh called his people for 950 years. Are those the years of this world? Also, we have narrations from them pbut that Noah pbuh lived for 2000-2500 years.
Moreover, the Bible says that early humans lived for a long time, meaning much longer than humans today.

Earth would fill with the knowledge of the Lord like water covers the sea

And what the text portrayed was not achieved in the time of Jesus pbuh, that the earth would fill with the knowledge of the Lord like water covers the sea, and this knowledge would have an impact that the rich would comfort the poor and that the strong would support the weak and that the earth would be almost free of injustice, etc.