Jeff Bezos’s initial dream was to build an everything store, that acts as a middle man between the manufacturers and the customers, that sold every product available. Since this didn't seem like a realistic goal in the beginning, Jeff decided to settle with selling books. And when this website was open to the public in 1995, it was the Earth's Biggest Bookstore.
And it was in 1998 that the company decide to move on to sell other products like music. Slowly during the years Amazon has started to sell clothes, makeup, tools, accessories, electronics, jewelry, toys, furniture kitchen utensils, and have even started to make and sell their own products like kindle. The only reason why amazon started selling products other than books was because that was why it was invented. And only then would it be called the everything store.