No here you are just straw manning people with different views than your naturalist ones.
The reason we want a human that can go beyond what is currently called human is that current humans are defective in both software and hardware.
On the hardware front our minds deteriorate badly after at most 80 or so years. That's simply too early for most humans to achieve any sort of intellectual maturity IE working software.
The length of our current lifespans were optimized around producing children but once you populate the earth you need longer than that to do the art etc. you propose.
Now I'm not saying their can't be prodigies that reach artistic maturity within a lifespan - just that our lives are too short for most of us to achieve that before death.
The problem facing enlightened liberals is damned if you do transhumanism and damned if you don't. If you do transhumanism then eventually the current primitive humans will be gone or greatly diminished. If you don't do transhumanism then we remain a species built for procreation but not much artistically interesting beyond that.