I'm simply drawing a distinction between something that physically exists versus something that doesn't physically exist. Ideas don't (physically) exist althou

I'm simply drawing a distinction between something that physically exists versus something that doesn't physically exist. Ideas don't (physically) exist although a representation of an idea can exist e.g. a mathematical circle doesn't physically exist, but representations of circles do exist and they vary with how close they get to the idea. With your guitar example, you demonstrate how we classify things in a messy way. Because the idea of a guitar doesn't exist, but lots of representations of guitars exist, we just refer to those objects as "guitars" as we can recognise the "guitar idea" that they are made to represent. Distinguishing between physical existence and non-physical existence is very useful - it allows you to separate the map from the territory. It's very useful to abstract the concept of "five" and recognise that it's different to five objects, despite them being so closely related. The abstraction of numbers becomes more useful when considering ideas such as negative or imaginary numbers - it would be difficult to reason about and use them if we continually think of numbers as only "counting objects".