Please, does anyone knows where I can download sprite images or where I can probably make them.
Tons of free and paid resources listed on the wiki.
https://opengameart.org/ (almost all free and open source)
https://www.itch.io (Paid & free and open source)
LibreSprite (Free version of Aseprite)
You can also find many in the asset store in Gdevelop.
Add object, on the top, choose the
search asset store. There you can find premade objects (tiled,sprite,9 patch,particles, etc…)