The human ability to anthropomorphize other animals and objects is a wild and crazy thing. Your cat can be staring at you intently because you are five minutes late in feeding them, and you somehow manage to take a picture and turn that image into something that summarizes a humorous and relatable moment. That's a big leap!
This isn't to say that our feline friends (or most of them, at least) don't have more going on behind their eyes than they're able to communicate effectively, it's just that the relationship we develop with them adds an extra dimension. It's what makes living with a cat or several so enjoyable, even when they're being little nightmares. They give an amusing touch to everything in both real life and in meme form. You don't have to have a cat to appreciate these memes, but you can probably imagine the situations behind them a bit better if you do.