We obviously do know what happens after death. We die and that’s it.
Actually, no one knows. You seem pretty hung up on providing 100% solid evidence; when it comes to an afterlife, we don't have much proof to go on either way. You like to compare the idea of an afterlife to unicorns, but unicorns like this are everywhere, especially if you are coming from another point of view. The universe didn't exist before the big bang, and then suddenly it did? That's a unicorn. There are 1018 stars in the universe, but no detectable lifeforms (a.k.a. Fermi's paradox)? That's a unicorn. Primal soup formed amino acids, then DNA, then cells, then humans? That's a unicorn. Quantum physics was considered a unicorn by Einstein.
And so it makes sense that one of the biggest unicorns of all – that one specific lump of organic matter called 'The Brain' would produce Consciousness and Qualia, even though they have no influence on the survivability of the body as a biological machine and thus have no reason to exist – is subject to fierce philosophical debate. Philosophers like David Chalmers use the 'zombie argument' to make a valid case that brains and consciousness aren't coupled in the way you propose at all, and it is in fact becoming mainstream in neuroscience that consciousness is a by-product of information transfer or even a property that all complex systems posses. When you think about it, why would 80 billion neurons lead to consciousness, but not 80 trillion transistors? Even your laptop might be conscious.
I'm sure you would call that a unicorn, just as I suppose you would take offence at the notion of 'free will', claiming that science has 'proven' we are deterministic machines. To dismiss all of these debates as being about 'unicorns' demonstrates a failure to grasp the full complexity of the discourse, ánd the nature of philosophy. As Paul Chamberlain said: áll truth claims must be proven, not just positive ones. The fact that many of the smartest philosophers debate these ideas to this day is not a testament to 'human irrationality' as you arrogantly put it, but to the fact that 'the hard problem of consciousness' is really hard. We just don't know enough about it.
And so when it comes to life after death, rather than bickering about the (non)existence of invisible unicorns, I would quote Wittgenstein: "Worüber man nicht sprechen kann, darüber muss man schweigen."
PS. I'm an atheist who doesn't believe in an afterlife.