Humans know that dolphins can be trained to imitate huan sounds, but only to the level hat their own 'vocal chords' will allow them to make sounds. But one man, back in the 60s, but a woman in a secluded tank with a dolphin for a month. She had a floating board, with a bed on it, where she could sleep. He did not ask her to train the dolphin to imitate her. He told her to just do what she wanted.
Being alone, with another living being, a human is prone to talking to it. This woman did just that. She would also play with the dolphin, with a ball. Eventually, as she talked to the dolphin, the dolphin learned that the ball was called a ball in English...a human language. By the end of the four weeks, this dolphin could communicate with the woman, what he wanted, what she wanted, etc. His grasp of the language was small, because dolphin's do not voalize the same as humans, but he could come out with a few sentences, and he understood the language.
This is an animal trying to bridge a communication gap, but it was impossibly to completely bridge it.
If that's a stupid animal, then by all means, kill them all for all I care.