it's not obviously achievable. for instance, we don't have the compute power to simulate cellular organisms of much complexity, and have not found efficiencies to scale that

Human level AGI only requires 20 watts

With a mechanism for AGI we don't comprehend at all.

Airplanes don't fly by flapping their wings.

knowing that a mechanism exists is enough to motivate us to find one that works with our current or achievable tech.

We were motivated to fly since the earliest human.

and we've had stories of artificial humans since we've been writing down stories!