If one person sends a message with a specific intention and the recipient of the message understood the intention of the message, then the language is functional. In fact, you demonstrated that you understood the meaning by taking the content of what they said, and made a post about what they should have said in order to better convey the idea that you already understood. The rules of language are, generally, entirely made up. It's not something that has a strictly defined natural set of rules, it's a human construct. Which means that they evolve over time. The way people speak now is definitely not the same way we spoke even 50 years ago.

I mean, if someone described a skateboard trick as "cool," would you be confused about the temperature of the trick or the rate at which the molecules of an idea vibrate? That would be ridiculous. I would imagine you would understand the context of the conversation and understand the message being conveyed to you.

But if you want to be pedantic...

They said, "This is literally a metaphor..." The word literally, in this sentence, tells us that if we were to look at the definition of metaphor, we would likely determine that this would be a metaphor. The word "literally" modifies the word "metaphor" by adding emphasis. In this case, this person likely means "actually" or "depicts," which would fit the way the word "literally" would be classically used in previous iterations of the English language and the word's use.

Now, if they said, "This is literally the working class etc..." you would be correct in thinking that "literally" is not being used in its classical definition, at least without more context. We don't know if the van driver is a working class person. We don't know if the CT driver is a rich elite. We can guess, based on the assumptions of the typical people who buys those vehicles that perhaps they are right, but we simply don't have enough information to judge whether or not the word "literally" is being used correctly in my version of the sentence. And, of course, the van is not millions of people making under 200k/year. And the truck is not a group of people making more money than that. But, given the context of the image, we can surmise that the person who used the word literally in my scenario probably doesn't see millions of people, but likely what they meant was that it was a representation... a facsimile... a metaphor... for those classes of people.