This is a better question to ask art historians. Pictures of fruit (and similar items) are called "still life" paintings. Their significance needs to be seen in context So, briefly: prior to the Renaissance, most paintings had a religious theme and painting a commonplace situation or people was unusual. As the renaissance progressed, still life paintings became more popular for several reason. They allowed the painter to show off their techniques, and, while fruits are to us the easiest thing to obtain at any store, they were much more prized in the 17th and 18th centuries, the height of still life painting. They represented a way to show off one's access to prized fruits that needed to be specially grown, perhaps in a hothouse, or transported from far away. In short, they were luxuries. Still life paintings also often included dead animals and household objects like dishes and pots and vases. These too were luxury items, representing some of the most valuable things the household contained. It was a way to show their artistic style and the harmony of their home, representing all of these different aspects of their wealth, their home, their hunting grounds, their agriculture, etc. It also showcased the painter's skill at painting immobile items. They could more completely show how well they could imitate life by focusing on these non-moving objects. In contrast, people who paint still life paintings today might not be entirely aware of all of this history, and might instead just be making a reference to a popular old theme, but without knowing why that theme was popular.