All it takes to become an artist is to make art. Did you have a terrible teacher criticize your drawings in middle school? Do you feel like you "aren't as creative as other people” sometimes? Do you feel like you don't fit the mould when you think of what an artist is "supposed" to look like? Artists come from all backgrounds and work in all mediums, and nobody is born a great artist. Art takes practice.
Artistic ability is a muscle that needs to be exercised. It doesn’t matter if you’ve never made art before—if you begin to create art and continue to create art, you can call yourself an artist. It doesn’t matter what stage in life you start to make art. You’ll get better with practice and exploration.