While their brain sizes were larger then morden day humans brain, sizes have very little to do with intelligence. Neanderthals were not brainer then modern humans. Neanderthal stone tools were rudimentary compared to modern Homo Sapiens from the same period of time. They didn’t stand a chance against the advances in intelligence made my modern humans.
Roman chariots were rudimentary compared to a Ford Mustang...the Romans were no less intelligent than people today.
We are Neanderthals.
Every feature that is used to describe Neanderthals can be found in Modern Humans today. For example, some Australian Aboriginies have a more severe brow ridge than did the Neanderthals, etc.