Different people should use different words.

I don't think a content creator would naturally describe themselves as a content creator. The word is useful for contexts where you need to generalize over all the different types, but that's not useful when speaking about yourself. So a writer says "I'm a writer", not "I'm a content creator." But writing this paragraph, I needed a word to generalize.

P.S. The closest alternative word might be artist, but it's not quite right--some writers are artists and some aren't.

I agree, and the audience also matters too. A writer speaking to writers at a writing workshop? "I'm a writer." A writer at an independent business conference? "I'm a content creator", as a means to relate to people making videos, blog posts, photographs, tweets, etc.

Some 'content creators' might also do: videos, blog posts, photographs, tweets, and a lot of other activity that drives the same business: getting user 'engagement' for sponsorship or advertising revenue.