What theories we laugh at now?
Ridiculous stuff like gigantic ass monsters beyond the sea, or that the Earth is flat and carried by a big guy. These things seemed sensible because of lack of knowledge and technology, same as today's theories of brains connected to a gigantic ass computer. Seems theoretically possible with today's knowledge, just like the sea monsters back then, but nobody has seen neither the monsters, nor Big Boy Computer.
500 years ago we lacked the engineering tools to actually test most of the ridiculous theories that got overturned later. These existed not because we were confident they were true, but because we tried to make sense of the world without the adequate tools to confront our models with reality. Or sometimes because of politics. There are plenty of examples of that now too, yet hardly a significant part of our knowledge is even moderately likely to be overturned. The ancients knew the properties of fauna and flora in their environment without understanding the chemistry and biology involved. Their knowledge was never overturned by later discoveries but merely put in context. Much in the same way, we know how to put satellites in orbit. Even formidable discoveries in physics can't change that.
Practical stuff, yes. Past people's practical knowledge wasn't false, it was mostly incomplete, but so is ours, and so will be future people's. But when it comes to theories about life and spiritual stuff, our theories are no more correct than the past or future people's. On a bigger scale of time, computer brains will turn out to be just a fad, something that appeared because people discovered a new bit of technology, and created a world theory out of excitement.
There are multiple ways how to do things and they aren't equally good. For example, there is a hole in the brick wall. You have oval shaped brick in your hand. After many attempts to put it in rectangular hole, you'll eventually mold it in desirable shape and force it into wall. Or you could be smart and pick the brick of right shape and size, just slide it in the opening.
But no brick will be perfect in shape and size
like my dick :^), you can come infinitely close to perfection, but there will always be a tiny bit missing. Same with world theories.