During the 15th and 16th centuries, there was a great demand for spices in Europe, such as pepper, cinnamon, nutmeg, and cloves. These spices were used to preserve food, add flavor to dishes, and were also believed to have medicinal properties. However, the supply of spices was limited and expensive, as they had to be transported from Asia by land or by sea, and the journey was long and dangerous.
At that time, people believed that the Earth was flat, and Jacques Cartier assumed that the ocean would lead him directly to Asia. He hoped that by finding a Northwest Passage, he would open a quicker and more direct route to Asia, reducing the cost of acquiring the much sought spices and making himself rich in the process.
In summary, the primary motivation for Jacques Cartier to explore and search for a passage was the desire to find an easier, shorter and cheaper access to the wealth and riches of Asia's spice trade.