The Gutenberg printing press was important because it allowed books to be printed in large numbers. This brought the price of books down and allowed more people to have access to books (and to other printed materials such as pamphlets). This was to have important consequences, for example, in the early 1500s when the printing press was used to spread Martin Luther's religious ideas far and wide.
Because of printing, people were able to become more educated. They were able to have better access to the ideas of others. This sort of thing helped to push the Renaissance ahead and to bring Europe farther towards the modern age.
By allowing printed material to be created relatively easily and inexpensively, Gutenberg's invention changed intellectual and social life in Europe. Therefore, it is very historically important.