I've created these royalty free backgrounds in Medibang Paint. Feel free to use these backgrounds in your own (non-commercial) projects. Please tag me or share a link to your finished projects so that I can see what you have created.
The Simpsons animation background:
African Savannah animation background:
https://art.ngfiles.com/images/528000/528851_aperturejam_african-savannah.png?f1592901731