Almost all graphics are free to use resources (i am not a graphics artist).
https://opengameart.org/content/animated-top-down-survivor-player
https://opengameart.org/content/animated-top-down-zombie
https://adamatomic.itch.io/jawbreaker
https://opengameart.org/content/free-top-down-car-sprites-by-unlucky-studio