Maybe the word primitive isn't the correct word, their language is no doubt more developed than most other Mammals on the planet, but is still likely primitive when compared to our own, this is based off of the Neuron allocation within their brain.

African Elephants have three times the number of neurons in their brain than we do, but 97.5% of their neurons are found in the Cerebellum, the Cerebellum takes sensory inputs and converts them in to coordinated and precise body movements, their motor skills are far greater than our own and this can be easily observed when simply watching how intricately an Elephant is able to use their trunk, controlling 40000 muscles in not an easy task!

The cerebral cortex is the part of the brain where most of the language processing functions are carried out, an African Elephants cerebral cortex is twice the mass of our own, yet our cerebral cortex contains three times as many neurons, as such our cognitive ability is far superior to an African Elephants.

Hope that's helped a bit!