Humans have new Brain genes that gives it advantage over Neanderthals. This derived Brain gene, TKTL1, was not present in Neanderthals or Denisovans. It plays an important role in the Pre-Frontal cortex development, a region of the Brain responsible for higher cognition, abstraction, working memory, logic and reasoning, planning etc.
https://www.science.org/doi/10.1126/science.abl6422
https://www.science.org/doi/10.1126/science.abl6422