Capitalism calls for the expansion of the figurative market that controls the global trade. In simple terms, capitalism made trading thrive. With global trading access, nations will have less of a concern for its population, and rather focus its economy on relevant subjects(like war).
Think of it like pie baking:
A group of pie enthusiasts can only consume pie, and they need the necessary ingredients for the pie. Some of them might have more dough than their other ingredients, so they need to rely on others for eggs, fillings, milks, etc. But coincidentally, the people that gives the ingredients also needs dough, so they trade, resulting in everyone being able to bake pies.
In real life, countries often rely on other countries for food source, material supplies, and labourers. Your computers are made out of minerals mined from the congos and Argentina, engineered in Germany, manufactured in China, processed in Vietnam, and finally sold to you as a western consumer.
Thus, capitalism creates global trades; accounting for the development of human kind.
Hope this helps!
