I don't think you need to fully understand how the brain works to be able to create AGI. Did the invention of the wheel/cart/car require us to fully understand

I don't think you need to fully understand how the brain works to be able to create AGI. Did the invention of the wheel/cart/car require us to fully understand how we walk? Did we need to fully understand how fish swim before we could make a boat? The only caveat would be that the AGI we build would be entirely unlike human minds. In the sane way a car going 100 kph is different from a running person.