When King Philippe II/III crammed down the Treaty of London on all his enemies and allies, settlements could be developed.
However, prior to that Spanish settlements on the mainlands were small and few in number. Spanish power in the Americas was seen mostly on the islands.
The Portuguese had no problem bringing in slaves to replace Indians ~ but in 1535 Spain took over Portugual and ended that for a while. That's what probably killed the economies ~ but I'll go further in this, there was nothing terribly important happen in the Americas beyond gold-mining until nearly the end of the 17th century. With the Thirty Years War out of the way, and Europes return to a growth economy, they had the resources to subsidize American ventures.
The 1700s are big time here with American born European origin populations rapidly achieving near European sizes ~ but not densities.
In North America absolutely correct.
Central and South America were a whole other story. The annual Treasure Fleet to bring back the bullion from the New World started in 1566, largely because the Spanish were forced to convoy by pirates and buccaneers.
Very little of the wealth it transported came from the islands. It came from Peru (mostly from Potosi, founded in 1546) and Mexico (mostly Zacatecas, founded about the same time)
Meanwhile Cuba, Hispaniola and Jamaica were largely depopulated by Spanish colonists moving to the Spanish Main, leaving Jamaica vulnerable to the English and western Hispaniola to the French.