Any info on why this was rejected for artifacts problem would be appreciated. New to this.
Unfortunately, the image posted is too small to point out the artifacts. However, most likely you either have signs of noise in the shadow areas and or, JPEG compression artifacts - pixels become more 'blocky' as a result of compression.. Especially noticeable when zoomed in and taken with a smartphone.
Zoom the image to between 100 and 200%. Take a close look at the typewriter's text hammers. You will notice they are not smooth black. There are a lot of colored spots. You will need to use the noise reduction tool of a photo editor such as Photoshop, or Lightroom to clean those spots away leaving smooth black color.