As to low IQ scores people with an IQ of 60 generally don't have anything that they preform very well. The problem is everything we think of as takes even something as simple as holding your hand steady is really complicated. Getting better at even simple motor functions takes feedback loops, effort, and optimization. Further, intelegence generally allows people to optimize more quickly even as an infant. Which means intelegent people not only get to optimize more quickly they have more time to optimize complex tasks or tasks they are worse at.

Specialization of course kicks in, but the sills a six year old has are fairly universal and things 98% of people can do. Intelegent people tend to be better at.