Why? I didn't say 'good artist'. If people regularly make art, then they're an artist.
Humans are inherently creative, yes. Having done both, I'd say being a parent requires greater creativity than, say, painting, or drawing, as it's a series of sometimes urgent problems, and any solutions you may come up with will suddenly stop working as time goes on, so requires constant thinking on your feet, where as drawing or painting is an excercise in looking and breaking down what you can see in such a way you can reproduce it. I always saw Marx's concept of species being as being about our greater ability to manipulate/work our environment compared to other animals, and that ability is creativity.
I think the mystique around the term 'artist' is really unhelpful, and prevents people from making art. Especially if they come from backgrounds which aren't 'arty'. People shouldn't be asked 'what makes you think you're an artist' they should be asked 'what art are you making' for example. In my experience, people who don't make art tend to buy into this mystique much more than people who do.