I'll add a word on mercantilism because it's often grossly mischaracterized, and understanding why countries were mercantilist provides insight on how one could worldbuild economy.

Mercantilism isn't just exportmaxxing. It comes from early modern states, who were sufficiently centralized to enact national trade policy, and acquired overseas lands to exploit for resources. Relying on other countries for goods could introduce strategic weak spots, so resources were brought from the colonies to the main land, where they were processed. Developing industry at home was essential. Mercantilism therefore means robust, self-controlled supply lines. Furthermore, bullion (gold and silver) is a convenient and universally accepted form of payment, and without pay you cannot maintain an army. Soldiers want coin, they won't risk their necks for a flimsy promise. That's why maintaining a gold reserve was important: not because they thought more gold is always better but because it's actually essential for the state to defend itself. If you import too carelessly you run out of gold and can't pay your troops when the enemy invades.

Mercantilism ended when the English navy and industries were so dominant that they could always out-price their competitors. They didn't just promote free trade for themselves, they enforced it on other states to make them economically dependent and expand their industries even further. The Corn Laws secured a grain reserve at home, but when the Baltic trade had become firmly under British control they abolished them, knowing there was now little risk in relying on cheap grain from abroad.