All the PNG images load fine in Godot so far, but when I use images for the floor, they become pixelated and look very different from the original. I want you to look at the image to see the big difference.
If you are using pixel art, make sure the image filter is set to “nearest” and not “linear”.
For 2D nodes you will find the setting in the inspector at CanvasItem > Texture > Filter
For 3D materials you will find the setting under the Sampling dropdown in the material properties.