Crediting artists isn't about whether or not you take the credit but that you are giving credit to the artist. If you know who created the art you are using, then reference the artist by name and where you found the art (usually in the form of a link to the webpage where the art can be found).
In Elements, no card can or will be used if the artist is not given credit. Several reasons abound for this, but most important is it's illegal to use someone else's work without getting thier permission and giving them credit. It be similar to me using your card exactly as you have written it, submitting it as my own work and saying because I didn't put my name on it, it's not wrong. You understand now why this requirement is necessary I hope?
Yes i now understand what you mean.. Its illegal to use another persons images without premission. Right? Well, ill have to use the pic that i made the Lernean Hydra just looked way cooler :-/
EDIT: Now i changed the picture to the one that i made so ill give the credits to me lol