Go ask a chimpanzee 😆

Okay, so forgive the glib answer, but yeah, obviously on the macro level our genetic differences with the other apes contribute massively to our difference in intelligence with them.

At the micro level - i.e. between individual humans - my understanding is that the evidence also suggests that genetic variations lead to variation in intelligence (of course, as mentioned by other commenters, the usual caveats of how exactly you define and measure intelligence apply.)

See: https://archive.is/9o5cy

Researchers found that the IQ of children adopted at birth bore little correlation with that of their adoptive parents, but strongly correlated with that of their biological parents. What’s more, this association became stronger as the children grew older.

In fact, hundreds of studies all point in the same direction. “About 50 per cent of the difference in intelligence between people is due to genetics,” he says.

Although each gene associated with intelligence has only a minuscule effect in isolation, the combined effect of the 500-odd genes identified so far is quite substantial. “We are still a long way from accounting for all the heritability,” says Plomin, “but just in the last year we have gone from being able to account for about 1 per cent of the variance to maybe 10 per cent.”

Also: https://www.une.edu.au/connect/news/2022/10/multiple-insights-in-a-decade-of-twins-data

The longitudinal Academic Development Study of Australian Twins (ADSAT) is the first project of its kind in Australia and has amassed revealing data on 2,762 twin pairs, 40 triplet sets and 1,485 non-twin siblings. Using the National Assessment Program: Literacy and Numeracy (NAPLAN), and regular parent surveys, it has given researchers a unique picture of the behaviours and demography that contribute to educational achievement – and the extent to which our genes influence them.

Genetic differences among students are the single biggest influence on differences in literacy and numeracy standing and growth, accounting for half or more of that variability across tests and across time.