@ graycyn --- another good source for free illustrations is
https://pixabay.com/
their "PRO" images have a fee, but they have a pretty good selection for free as well.
You need to set up a free account to download more than a very limited quantity daily, but well worth the trouble --- they have line art and other digital art, as well as photos, which sometimes are preferable. (And lots of clip-art, if you ever need that)