Taking copyrighted artwork from artists and not crediting them is illegal. Passing yourself off as the artist of a commercial piece of art, while you're not, is illegal too. You'd be looking at a fine that'd be a rough estimate of $300,000 in compensation value. You've done this for all card ideas you've posted so far. It's illegal, disrespectful and just wrong.
I'd suggest you take artwork you either actually made yourself, royalty-free artwork, or no artwork at all.