Our Universe appears to be expanding and cooling, having originated some 13.8 billion years ago in a hot Big Bang. However, it's plausible that what we see from inside our Universe is simply the result of being inside a black hole that formed from some parent Universe. If the black holes that form in our cosmos give birth to baby Universes, perhaps we arose from the formation of a black hole ourselves.
That's what I'm saying though - the hypothesis that we exist in a black hole does contradict the evidence currently available. Or at least I think it does - I opened the contractions initially as a question because this isn't my area of expertise. I've had a few relevant classes, and have a casual interest in the topic, so I think I have a pretty solid foundation at least; but ultimately I'm just a medic, so I was kinda hoping someone with a more dedicated background would chime in.
There's a LOT of BS surrounding the topic of black holes - and understandably so. They're intriguing as hell, so it's no wonder that they're so often the object of artistic freedom. But all's fine and well to proclaim that they're some kind of portal, or mini universe, or cleverly disguised alien spacecraft, or even a sentient creature... in the context of science fiction. But to say any of those about black holes IRL should come with supporting evidence, especially if some aspect of the proposal clashes with our current interpretation of what we can either directly observe or indirectly postulate.