Aside from differing levels in what you can directly sense with your tongue– Sweet, Salty, Bitter, Sour, and Glutamates (umami), which we would all consider to

Aside from differing levels in what you can directly sense with your tongue– Sweet, Salty, Bitter, Sour, and Glutamates (umami), which we would all consider to be 'seasoning' elements (not broaching the topic of different chemical effects, such as with capsaicin)– the primary difference between any two foods is how they smell, which is why when you have a totally blocking cold, you can easily tell if something is too salty, but you couldn't say what herbs were used in it. Consider a lime lollipop and a cherry lollipop with the same ratio of sugar base to whatever acid they were using for sourness. Going strictly by your sense of taste, maybe because of Anosmia, they would be utterly indistinguishable. The flavoring components, however, which really just give the pops a scent, are what makes the lime one taste like lime, and the cherry one taste like... whatever cherry lollipops are supposed to taste like. Our brain combines the tongue sensations and smells (and arguably, its appearance, mouthfeel and sound) to create our perception of something's 'flavor.' This is why seasoning food, especially with salt, is important. It's not going to change the intensity of the brownness of a steak, or the freshness of an ear of corn, but it stimulates the tongue in a way that makes our brain much more aware of what we're smelling. It turns up the volume on the existing flavors, as if to say "hey! pay attention to what you're smelling, because it's coming from what's in your mouth." (I imagine this evolved from a combination of our need to seek nutrition, as well as our need to detect poisons.) Lacking stimulation on your tongue, foods come across as flat and uninteresting. I'm sure our bathrooms would be designed very differently if our brains were worse at making the distinction between what we're just smelling, and what was in our mouths.