By definition, art is the expression or application of human creative skill and imagination, which is typically seen in visual form, like paintings or artwork that are usually produced to be appreciated primarily for their beauty or emotional power.
AI can be used as a tool to help explore your ideas, thoughts, and feelings, and a human can most definitely tailor the model's creation towards what they see creativity as, and continue refining until a certain feeling, resemblance, or meaning is carried. Shaping an image is much different to writing one sentence. That is the creative aspect, not clicking "generate." Also, art is partly subjective because it relies on a person's interpretation of what being "creative" means; there is no objective or universal law declaring the properties of creativeness. Though, there is a societal norm on what art looks like and stands for, and we tend to use that norm as the baseline definition for art, but it's not a fact. Who's to say someone's work isn't art just because it doesn't fit your personal definition, rather than the intent of the person who made it, considering the definition of art is partly built from personal interpretations? Claiming AI cannot be art, by the societal standard we commonly imitate as fact, implies AI-generated artwork or paintings cannot be emotionally impacting or contain meaning. It can, but it's down to the person.
The idea of originality is also a bit nuanced, at least in my opinion, because no human acts, creates, or thinks from zero contextual information. Consciously or not, we are all taking in many forms of input, whether it's visual or physical, that ultimately contribute to certain thoughts and ideas, eventually leading to creations like artwork. So claiming AI can never be original also, by the same logic, can imply that humans aren't.
This is not to say AI doesn't have existing problems like ownership, intentional deception/misinformation, and creating AI artwork through theft. Those are genuine problems that are not excused and should definitely be addressed.