Do all languages progressively get more complex? The degree of such complexity varies greatly between languages and is affected by a variety of sociolinguistic and historical elements, including language interaction.

First, it has never been measured how complicated a language is relative to another. This is due to the fact that it is hard to measure; for instance, how does one unit of phonological complexity relate to one unit of syntactic complexity? The parts of pragmatic complexity can be found or counted in what ways? These questions have not been addressed, hence there is no concrete proof of this “truth.”

It is not certain that two competitors who compete in separate events finish in the same amount of time because they might have been running at various speeds during their respective events. Once more, it is considered that all people acquire languages equally quickly and are equally capable of learning a first language. This is not accurate on a superficial level. People who are deaf cannot learn spoken languages. Not only that but there is also evidence that different persons have varying degrees of skill in their first language. This is plainly apparent in people’s varying levels of eloquence, for instance, but it is also quantified in the lab: research has revealed, for instance, that some native Cantonese speakers are unable to discern the tones of their own language. Thus, learning the first language takes various amounts of time for different people.

Second, there isn’t much—or any—cross-linguistic research that demonstrates how young individuals can grasp multiple first languages. In fact, it appears that the reverse is true: English morphology is learned before Georgian morphology, speakers of some Native American languages reportedly do not become fluent in their mother tongue until adolescence, and people’s linguistic abilities alter over the course of their lifetimes. In the end, no one has developed a non-circular definition of fluency, and there is no conclusive evidence that people acquire various native languages fluently at the same age. Thus, different languages tend to be mastered by people of various ages.

That’s undoubtedly accurate on a few key levels, as well. English has straightforward phonology and morphology, but Georgian has fairly complicated phonology and morphology. English has a little advantage, although syntactic complexity is almost similar. These are the factors whose complexity can be openly quantified, therefore you might conceivably claim that Georgian is more complicated. There are significant disparities in aggregate complexity between languages when you consider the layers of linguistic organization that we can quantify.

People who speak English are able to characterize complicated things in terms of what English lacks at the level of relative perception. Languages having complicated case and agreement systems, as well as tonal phonology, would thus be characterized as complex by English speakers. In light of the questioner’s apparent use of the word “complicated,” I don’t see any issue with this.

To answer the original query, it would appear that relative isolation from other languages and the number of speakers are two elements that contribute to complexity. Examples of this would be Icelandic and Georgian once more. 

On the other hand, it would be less complicated if there were big speaker populations and frequent communication with other languages. Chinese and English are also present here. Chinese? Indeed. The Chinese languages have a simpler morphological structure than English if there is such a thing (and Vietnamese).