(Summary:) There is no cause to suppose, even if the human genome 100,000 years ago had the full set of IQ-related-alleles present in our genome today, that they would have developed civilisation much sooner.
(Rhetorical nitpick:) You gave an argument against one such cause. This doesn’t mean there are aren’t other causes, and it’s not clear that your argument is decisive.
(Rhetorical nitpick:) You gave an argument against one such cause. This doesn’t mean there are aren’t other causes, and it’s not clear that your argument is decisive.