There are many ways for language to be complex, and most of them have nothing to do with the actual structure of language. Consider the sentence:
I feel you.
I am talking to a friend, and they express frustration. Then I’m saying that I understand what they’re going through and trying to validate their feelings. But the extent that they actually believe that I understand them is really up to a lot of things including their impression of me, our mutual interest, and the kinds of emphasis I put on “feel” (not to mention whether that emphasis has special meaning in our relationship).
An employee is responding to a client’s surprise at the rise in prices of some product or service. Here there is still a sense of empathy as in (1), and yet it is clearly an attempt to bridge over discomfort caused by an entity that the speaker represents in name, though they are not in control of it. The empathy is likely honest as it is easy to understand the customer’s feelings, but it just as well may not be: the employee may be tired of this troublesome customer, a fact that the customer may be duly aware of or not.
A parent responding to their child very lightly poking them to see if the parent is awake. The parent is explaining that because they are conscious, they connect the physical sensation with the phenomenon of a poke, and more specifically of a child trying to get attention if it is there to be given.
Should we be surprised that there are very different ways to use the same words? Hardly. This is not just a matter of “sense”, (1) and (2) represent the same linguistic sense, but (2) can be a mockery of that sense. So what it is going?
Words point at things i.e. “shared” parts of reality, but the word “shared” is altogether misleading: we do not really share anything about our perceptions of reality. Rather, some of the experience is similar enough between people and the words used to refer to it are similar enough between people that we can use words as the translation between maps.
Language solves a coordination problem. This coordination problem is impossible to solve perfectly. There is no isomorphism between two people’s conceptions of reality that preserves semantics. People conceive of different elements of reality, for instance the experience of pleasure, so differently and these differences change the way they explain adjacent concepts and words. It is tempting to deny this and say people disagree on their opinions, but they can conceive of other people’s realities. This is true, but it is only true insofar as people are capable of conceiving of how something could be different for someone else, but someone without the experience of, for instance, being pregnant, may never have access to a similar enough experience. It is easy to point to physical situations like this, but I imagine this inability to conceive of the other properly is only more common with emotions.
How does language do it? It does so by being discarded when it is useless, and by taking advantage of parts of our brain (e.g. Wernicke’s area) that make it easy for the next generation to get up to speed with what people are already using. That’s right: language is mostly an evolutionarily optimized object. Language changes faster than genes, as when it changes for a person over their life these changes are heritable, but its change is nonetheless limited by transmission.
How have we gotten so good at coordinating with it, even though we don’t know the depth of people’s inner worlds? We were all born into a world with language and our inner-worlds were molded by language and we learned to navigate them through language. Think of all the times you’ve written something down to try to feel it out. I doubt our inner worlds are really so well-mapped by language, but our urge to coordinate is so strong, that’s what we end up seeing in ourselves.