Not only Columbus navigated trade routes in the 15th century. Two others stand out.
Zheng He was a Chinese Muslim, famous for his 400-foot long ‘treasure ships’. He was a very successful Indian Ocean trader, receiving tribute in exchange for trading rights.
Portugal needed imports, and developed a school of navigation. Vasco Da Gama sailed to find the Indian Ocean, for the spice trade, as well as a mythical kingdom in Africa. Portugal captured a few ports, but lacking the resources to trade effectively, resorted to extortion and piracy.
Following the Portuguese example, Columbus sailed in search of the East Indies. An excellent navigator, he underestimated the ocean’s size and happened upon America.
Which was the greatest? Zheng He was vastly more effective at the time, but the after-effects of Columbus’s journeys are stronger.