If you make a little game without any intention to sell it, I don't think you'll be in trouble. I used to use rips from this website a lot when I was making RPG Maker games a few years ago. Very useful.
These sprites can be used in two ways. for personal use and practice with sprites and other events is to download them and edit them completely, there are people who can not coom I draw characters with movement and used to modify the sprites above. It's like tracing paper drawing.