To circumvent this issue you can look for free art online, rip from other games, or buy general purpose art packs. This is what we did. To be able to properly test our sprite animation handling, attacking, movement and other things, we purchased the GarageGames 2d Fantasy pack, which contains animations of movement, attacks, and other cool stuff.
The pack cost us 30 usd, which fit well on our small pockets and allowed us to have some solid placeholder art.
You can see the small version of the skeleton sprite on our fifth video. The animation still had some bugs by this point, and the video is a little laggy, so excuse me for that part.