If you upload a song by WMA to youtube, you are not stealing but sharing, no law can tell you stole that song.
The Digital Millennium Copyright Act is specifically made for the purpose for the copyright holder to be able order a cease and desist on works using their intellectual property without express written permission. Many countries have adopted their own version of this law to be able to trade with the World Trade Organization and to be accepted into the United Nations.
Physical property is treated differently than intellectual property so the examples of the hammer really don't have much to do with this. To make that clear, though, if you steal your neighbor's hammer to create a masterpiece the neighbor has no right to the masterpiece created. They can however demand legal action and compensation for the act of the hammer being stolen.
You can't rise anything against the uploader unless they SELL their works made by a brush from another artist.
Even if you upload something and call it your own works, even though you didnt make any of it, you can't sue em, because they are just sharing.
Even if you are not making a profit from use of an intellectual property, if the original copyright holder sends a cease and desist letter, the uploader has an obligation to remove that artwork. The uploader can choose to redo the artwork with a different type of brush from that point. If you didn't make that art yourself and the copyright holder tells you to remove it, you are also obligated to remove that artwork even if you are just sharing it. An example of the latter is when a website that hosts manga is asked to stop hosting a specific title they must remove all content related to that series.
But you see the problem is that most licenses (except the non-attribution one) specify that even for personal and non-commercial projects credit MUST be given.
This depends on the type of creative license they give to the property but by default you must give credit to the original author unless the author states otherwise. This is why you see many of the big-name Deviant Art users providing links and/or names.