Muhammad and “to err is human”

Muhammad was just a human at the end of the day. I do not understand why we have to keep bringing him up when clearly he is just a man. Prophet or not, but just a man. Also, 
 even according to the Quran

Surah Al-Isra (17:93): "...Say, 'I am only a man like you, to whom has been revealed that your god is one God...'"

But any logical person with an IQ below 80 should be asking the question. If you doubt even a little bit of the character of Muhammad, the whole of the Islamic foundation falls apart.

The first crack appears in his relationship with women. He is married 5 times, but Muslims are only allowed to marry 4 times. There’s no justification for that. He kept sex slaves (I know a pretty common thing in arab times, and if that’s correct, the Pakistani army did nothing wrong, raping women in Bangladesh in wartime.

How do you become a beacon of morality when you are literally taking part in sex slavery? Pedophilia? It is a bit hypocritical.

Then again, leaders are not black and white; they are supposed to be grey in their morality. Is Muhammad a great leader? Hell yes. But simply not a great person, definitely not Al-Amin. I will write