Final answer:
Hernán Cortés' main contribution was the conquest of the Aztec Empire, which had significant implications for wealth accumulation for Spain and the expansion of the Spanish Empire in the Americas.
Step-by-step explanation:
Hernán Cortés' main contribution to the discovery of the New World was the conquest of the Aztec Empire. While Cortés arrived on Hispaniola in 1504 and played a role in its conquest, his most significant impact came from his expedition to the Yucatán Peninsula. In 1519, Cortés and his men entered Tenochtitlán, the capital of the Aztec Empire, which they ultimately conquered after a series of battles and strategic alliances. This conquest not only led to a considerable amount of wealth for Spain in terms of gold and other riches but also paved the way for further Spanish expansion in the Americas and the establishment of the Spanish Empire.
The brutal conquest and the subsequent establishment of Spanish colonies dramatically reshaped the social and political landscapes of the Americas, leading to the demise of the Aztecs, the forced conversion to Catholicism, and the implementation of the encomienda system. It was during this era that Europeans became awestruck by the intricacies of the Aztec civilization, including sophisticated causeways, gardens, temples, as well as horrific practices like human sacrifices.