Why is AI not intelligent but humans are?

Sure this question comes up all the time, but I looked up the definition of intelligence on Google, and it's The ability to acquire and apply knowledge and skills, AI meets that definition. If it doesn't what is the human brain doing that is different?

I was thinking about the mental processes that go on whenever my brain wants to form a sentence. To me this happens, a rough concept of what I want to say appears in my head without words really, then a word appears randomly, which makes the concept A little clearer, then another one and so on until the sentence is complete. There is no real thinking about which word I'm going to use next it just appears. Sometimes another part of my brain will activate and say "that word's not right", then I will have to go back and repeat the process, but there's no real choice going on, to me it's all just a bunch of parts of the brain communicating with each other.

If you wanted to make the argument that AI is not conscious I could understand that, but to say that it's not intelligent, I just don't understand that opinion.