Going to make an assumption on how you did assets so feel free to correct me if I'm wrong. It looks like you scaled your character assets down to fit within the constraints of the size you felt comfortable with for your character (like scaled it down to fit within the hitbox). When you scale down the assets, Godot or whatever you're using to render your assets into .pngs or .jpgs, is going to make assumptions about the pixels. So like, if you scale the guy down, they lose pixels (scale it up, makes guesses on where pixels should be to maintain the look of the image).
Going to take some math and guesstimation but I would figure out what size you need to draw the assets on your whiteboard to avoid scaling. It actually looks like you may have a size that could work for a character based on the guy in the background.
