Where to begin with this fallacy
Lets say Malia was pure animal during her time in the woods
Animals are not stupid. They grow emotionally and learn from their experiences. In fact, they do it much more quickly than humans because, as we all know, they live much shorter lives.
That brings us nicely to the most important point had Malia been purely animal she would have matured to full adulthood and couldve produced a litter of pups during her first year.
Basically, after eight years, she was a middle-aged coyote, smarter and more experienced by far than most human teenagers.
But Malia was NOT purely an animal during those years. In her speech to Stiles in Echo House she explains her full awareness of her situation.
Really, after that scene, it is simply insulting to the character not to acknowledge her intelligence and instead portray her as some stunted child-like braincase.
She is more mature than her fellow characters because she has lived and survived on her own for so long.