The only limit to the "form" of language, and the categories of words used, is the imagination. One of the invented languages I have come across is "Allnoun" which is, er, all nouns. There may be philosophical (or philological?) arguments about the different uses to which words are put, e.g. nouns acting as verbs. A basic life form (with the intelligence of dogs, perhaps) might just have a few words to indicate basic needs and desires, in which case a grammatical structure, and grammatical categorisation, may not be needed. (e.g. "ouch!"
"food!"
"water!"
"look out, there are llamas nearby!" and
"let's have sex!")