Answer :

The most important skill developed by the hunter-gatherers were the tools that they crafted by hand. Such as bow and arrow, spears, shields, and other weapons to defend themselves from harm and to hunt for food. Whereas the gatherers which are mainly women, craft bowls and other jugs that help store the food for storage in their homes with water and other types of resources that they need to sustain life.
I think the most important skill developed by hunter gatherers was the Invention of wheel. As it was a new step to the evolution of humans and one of the greatest invention of all time which is very necessary for today.