>Also not saying everyone can do this but there are people that were facing death and have killed sharks, bears and various big cats.

It's more, I would say, laughing at the absurdity of the confidence and certainty. Sure, people have had exceptional outcomes in life or death situations (though with the sorts of ones you mention, they are more often matters of dissuading the attacker from continuing, especially since sharks and big cats often don't want to get into protracted fights).

But a cow of the sort shown in that list is probably going to weigh around 600 kg, and bulls, when angry, are extremely dangerous; probably more dangerous than a horse. Even with horses, control of a horse as an individual is based, ultimately, on it deciding to do what you ask it to do; they tend to be most dangerous, and can easily accidentally kill someone, when they are panicking. Meanwhile, seals can be much heavier and more agile than they seem when seen out of water. These are not "50/50 chance" situations. And with sheep in some "I'd have no problem" category: a friend of mine who works with animals points out with annoyance that people unaccustomed to livestock often joke to her with confidence and bluster about what they'd do if a ram tried to attack them: she points out that, no, if a fully grown ram wants to fight them, that would probably go very differently than they expect.

If anything, the list is both hilarious and annoying in how it seems to be entirely built around stereotypical perceptions of animals as 'cute', 'violent', 'giant', 'tiny', and so on, without it necessarily making much sense. Trying to fight a cow or a zebra is probably going to be much more dangerous than trying to fight a cheetah, the reverse of what the list suggests people think, because cheetahs are comparatively small, skittish ambush predators that are going to run away from a fight. There's often just a complete misunderstanding of the weight and strength of seemingly cute domestic animals. And while it's presumably there to be completely ridiculous, you're not going to lose a fight with a large baleen whale, because a large baleen whale is not going to get into a fight with you.

But in general, there's a weird obsession of people about how they could beat up animals.