Charles Quint (by Titian, 1548)
The biggest worry that people had in the early 1500s AD in Europe was that the Ottoman Empire was going to conquer Europe and Europe would be ruled by Islamic rulers. And in fact the Ottomans, under their sultan Suleiman the Magnificent, did conquer the eastern half of Europe during the 1500s AD.
Fortunately for Western Europe, the ruler of the Holy Roman Empire (modern Germany and Austria) was Emperor Charles V - an extremely skilled ruler. Charles also had inherited the rule of Spain, Portugal and the Netherlands, so he controlled most of Europe. With the discovery that there were two large continents - North America and South America - between Europe and China that Europeans had not known about before, Charles V also ruled the land the Spanish conquistadors captured in Florida and in California, Nevada, Colorado, Utah, Arizona, New Mexico, Texas, Mexico, Central America, and South America. Charles Quint also sent Magellan on the first voyage around the world, and so he succeeded in conquering the Philippines. Charles Quint and many of his subjects got very rich by forcing Indian and Safavid ships to stop trading (often by burning their ships) and taking over the trade between India, Africa, China, and Europe. In addition, Charles' Holy Roman Empire enslaved many Central and South American people and forced them to work in silver mines, especially in Peru.
King Francis I of France tried to fight Charles V, but not very successfully. Francis made an alliance with Suleiman against Charles, and several times attacked northern Italy, but he mostly lost his battles. Charles also succeeded in fighting off Suleiman's attack on Vienna in 1529, and even got to take over part of Hungary. Francis tried to get control of some of North America, sending explorers to Canada and to Manhattan Island (where New York City is now). Francis also sent trade ships to India and Indonesia, but still Charles V controlled much more land and more of the ocean trade.