You seem to be equating language with communication, and it is not just a matter of complexity. There is not only the use of abstractions but also encoding ability of language which rivals (and surpasses) DNA in it’s unlimited potential to transmit information. This is what enables language to be the substrate in the self-organization we call the human mind which has all the characteristics of a living organism in its own right to rival that of biological life. But seeing as how it is not limited to the rule of no inheritance of acquired characteristics, its evolution proceeds much faster.
I would love it if the cetaceans rivaled us in intelligence and had something like language as we had considerable hope for all while I was growing up. But this isn’t panning out. In some ways what they do have is rather remarkable but the evidence isn’t supporting the idea this is language and there are reasons to believe their intelligence is not as high as we first supposed either. Apparently the cetaceans are able to communicate some of their sonar data with each other. It would be like an ability to send pictures of what we see to another person directly. Though now that I think about it we can do that to some degree indirectly with descriptive language. Thus it is largely about their need for a way of locating herd members in a 3d space. Furthermore, it seems that some of their brain to body mass ratio is due to the difficulty of breathing while they sleep in the water.
Yes, this has always been of considerable concern in science fiction as we contemplate encountering aliens. But it is demonstrable that it is not just a matter of being different because they do not even begin to rival us in the acquisition and communication of information. Because of this, the biggest changes in their way of life tends to come from us.
I believe I already answered that with my comment on pigs. To the degree that they can use language to communicate with us, they ARE human. If they can communicate comparable to a handicapped child then they should be treated as a handicapped child. The point is that I do not support any magical differentiation by inventing “souls” comparable to Carl Sagan’s dragon in the garage to distinguish human beings from animals. I will go with what is actually demonstrable.
Like other science fiction writers, the encounter with another sentient species is the sort of thing I think and dream about all the time. And I am not one who favors the idea of aliens who come all that way just kill us or take away what we have. The difficulties of the vast distances do not really support this idea. Far more believable are ideas of voracious alien life which simply consume everything in their path without the slightest intelligence whatsoever.