@Mods..am only answering this brothers questions to give him the information he asked for..plz don't delete this post saying I am doing religious discussion..the brother asked a very good question and I have to answer it.
@A.P. Richelieu Although there is a verse in Quran which states killing one man is like killing all humans...but the context is different...it was actually a jewish instruction that was just mentioned in quran in certain context....The said verse is from chapter 5 verse 32 ..let me quote it for you
" That is why We ordained for the Children of Israel that whoever takes a life—unless as a punishment for murder or mischief in the land—it will be as if they killed all of humanity; and whoever saves a life, it will be as if they saved all of humanity.1 ˹Although˺ Our messengers already came to them with clear proofs, many of them still transgressed afterwards through the land. "(Quran 5-32)
The context of this passage is Allah is telling the story of Adam's two sons and how one son(cain) killed the other(abel).
It is in this context Allah says that
he ordained israelites that killing innocent is killing all humanity...This story with those exact words was already present in Talmud(jewish law). Let me quote a commentary of the same from Talmud .
" We find it said in the case of Cain who murdered his brother, ’the voice of thy brother’s blood crieth out’ and he says, ’it does not sayeth he hath blood in the singular, but bloods in the plural.’ Thou was created single in order to show that to him who kills a single individual, it should be reckoned that he has slain the whole race. But to him who has preserved the life of a single individual, it is counted that he has preserved the whole race. "
I will quote you a verse from the same chapter how allah instructs directly to muslims.
"O believers! When you rise up for prayer, wash your faces and your hands up to the elbows, wipe your heads, and wash your feet to the ankles. And if you are in a state of ˹full˺ impurity,1 then take a full bath. But if you are ill, on a journey, or have relieved yourselves, or have been intimate with your wives and cannot find water, then purify yourselves with clean earth by wiping your faces and hands.2 It is not Allah’s Will to burden you, but to purify you and complete His favour upon you, so perhaps you will be grateful. "(Quran 5:6).
Wherever Allah has commanded.instructed or advised muslims directly he says,
" O you believers" followed by the command.
This so called killing humanity verse is actually an instruction given to Jews .
coming to next part of your question
,"Is there any place in the Quran where Muhammad states that insulting him is worse than killing all humanity?"
Ironically, the verse next verse that follows this killing humanity verse mentions death to people who insults allah or his messenger.
" Indeed, the penalty for those who wage war against Allah and His Messenger and spread mischief in the land is death, crucifixion, cutting off their hands and feet on opposite sides, or exile from the land. This ˹penalty˺ is a disgrace for them in this world, and they will suffer a tremendous punishment in the Hereafter." Quran chapter 5, verse 33.
This verse is used to justify the killings of anyone who insults Mohammad .
Hope I answered your question.