My issue with "Transhumanism" is mostly that I don't believe that consciousness can exist as a result of material arrangements without a material antecedent, for which we have precisely zero evidence.
In other words, there's no proof that consciousness is an emergent property of matter. Actually, there's no proof that 'emergent properties' exist at all, merely emergent patterns of which consciousness is self-evidently not one. Either Consciousness is totally distinct from the physical properties of matter, or all matter is conscious down to the sub-atomic level.
In this case, the former is actually more likely than the latter. Occam's Razor essentially demands the existence of a "soul," a consciousness distinct from matter that constitutes the consciousness, as we have every reason to believe that matter is *not* sentient in and of itself, as machines and devices do not move themselves, they are moved. Purely reactive. Consciousness is the ability to self-motivate.
In brief, we have never, anywhere in nature, observed a trait to arise without antecedent in matter EXCEPT in the case of consciousness, which leads me to believe that it is not a material trait at all.
In other words, "we" are not bodies of flesh and blood. We are not brains. We are not anything. Consciousness exist in some other state, tied to these machines of flesh and bone, and any claim to the contrary is literally irrational, It is a denial of logic.
Therefore, transhumanism is deeply problematic, because it makes materialistic (which is to say, categorically false) assumptions as to the nature of human consciousness. Even the concept of AI, under this model, is impossible. Consciousness is not a material property, so it is not possible to make a conscious machine. It defies logic. It doesn't matter if you build a Chinese Room to perfectly emulate human behavior and reasoning, that isn't what consciousness is. We don't know what consciousness is.