Yeah.... they likely don't have much of a chance of winning this. You have to show that you've been actively using and defending your copyrights...
Wrong wrong wrong. Copyright does not require you to defend your claim, and in fact you are permitted by law to engage in whatever utterly arbitrary licensing schemes you choose (including accepting and rejecting licensees at whim, or ignoring an infringement for years before deciding to go after it) without penalty.
Trademarks, on the other hand, may be legally lost if not defended.
Couldn't such a small reference fall under the protected category of "parody," though?
Nope. Parody defense requires directed mockery or satire of the target, not just general humor that incorporates the target. Neither meme is being directly satirized here.
Because those characters got famous ONLY BECAUSE people took those characters and made technically illegal copies/replications/modifications. There were hundreds of thousands of infringing works all over the internet...that's what made them famous in the first place.
I don't see anything wrong with turning a blind eye to fan-made and not-for-profit derivative works while being more stern with for-profit infringement... in fact, that's exactly the standard we generally apply to big corporations (who we expect to allow fan translations and love-letter fan games, while stepping in to stop paid infringements.)
I just don't think a homevideo of an animal doing something stupid should be considered creative property.
All creative work is automatically copyrighted in the US and the other signatories of the Berne Convention. If you take a photo, shoot a video, hum a song to yourself, it's copyrighted. That's what we do to ensure creators have some control over -- and, maybe more importantly, ability to make money off of -- their creations at the instant they come into being.
The only things copyright-able by the laws of my country are
...everything in question in this thread, because Spain is a Berne Convention signatory and therefore the copyright in Spain for all the items under discussion here is only dependent on its status in the US, where Nyan Cat, Keyboard Cat, and Scribblenauts were all created.
Now if they were to create a legitimate product, like a song or a movie
Luckily for the creators here, there is no country on Earth whose laws agree with your ridiculous definition of "legitimate product."