By your definition most of what we consume are "chemicals". Especially since most of the eliquid ingredients are commonly found in processed food....I think both terms... ingredients and chemicals are both accurately used. The term chemical in this case is a more specific term to classify the ingredients.
Propylene Glycol is a chemical... same with vegetable glycerin... nicotine in it's liquid form would be accurately termed a chemical and it's mixed in a base of either PG/VG or both. Then there's flavorings... if you look at the ingredients of the artificial food flavorings used in most e-juice... they are pure chemical concoctions that contain no part of the source flavor they mimic. Here's a good example: http://www.johndwalsh.com/MSDS/FLAVORS/Blueberry,Artificial059100A.pdf