Always make sure you have some transparent pixels around your sprites. Sprites are saved to a spritesheet which copies multiple individual sprites to a shared spritesheet. What you are seeing is bleed from another sprite. I can see a black line on the player. If you export your project and look at the spritesheets, you can actually see that sol2 is placed next to your player. It's black border is bleeding into the player when the graphics are scaled to the screen. If you add a pixel all around sol2, the line disappears from player.