As someone who did a lot of research myself for various uses-there's quite a few sources for those who aren't very good at arting for finding good, high quality art-for free! (Don't forget Itch.io also has a lot of free packs!)
Note: CC-0 is short for Creative Commons 0 license. This means the piece is FREE to use for ANY PURPOSE! Without credit! It is still good to credit your stuff and where it came from. Always read what ways you can use a thing! ROYALTY-FREE DOES NOT MEAN FREE. Those may include a purchase but are free to use however once you have them!
https://www.pexels.com/photo-license/ - CC-0 photo source. Ungodly amounts of free photos.
https://opengameart.org/ - Lots of varying arts for all sorts of purpose. Not everything is CC0! Please read the requirements for each piece!
http://freemusicarchive.org/member/Alpha_Hydrae/Awesome_CC-By_CC0_and_PD_music Crap ton of free music.
https://www.bensound.com/royalty-free-music/ Royalty-free music and a bunch of freebies.
https://www.makeuseof.com/tag/14-websites-to-find-free-creative-commons-music/ A resource for more music!
https://lemmasoft.renai.us/forums/viewtopic.php?t=17302 Uncle Mugen's free VN backgrounds
http://soundimage.org Music and sounds of all sorts!
Hope this helps!