the way you've described this makes it seem like you're putting the skin files directly into the resource pack folder, which is not where they go. you first need to make a resource pack like the duke is describing and then put the files in the exact directory of the original texture (this will vary based on edition and version). the cat paintings seem to already be packaged as a resource pack, so you can use that as a base.
also, the bobber is for bedrock edition and will not work on java edition without some modding.
