Oggers you are overlooking the power that is being wasted in doing work on the propwash.
When the aircraft is stationary on the ground with engine running all of the propeller power output is being wasted in accelerating the propwash rearwards. So none of the propeller power output is being delivered to the airframe. That means that there is no THP, because as Barit has said "THP is the power delivered to the airframe".
In theory if the aircraft were to fly at its own propwash speed no power would be wasted in the propwash, so all of the propeller power output would be being delivered to the airframe. So it would all be THP. This is of course only true in theory because if the aircraft was flying at its own propwash speed, no air would be being accelerated rearwards by the propeller, so there would be no thrust.
At any speed between the zero and the propwash speed some of the propeller power output would be being wasted in the propwash and the rest would be being delivered to the airframe as THP.
If you think about it this means that the propeller power output is the THP plus the power wasted in the propwash. So we cannot say that propeller power output is THP.
BUT. If you look at any fixed wing diagram of power available against power required you would see that the power available is the THP. It would perhaps be better to say that this is the USEFUL power available.
Your mistake throughout this entire thread has been in assuming that THP is thrust x propwash speed. It is not. Beacuse THP is the power being delivered to the airframe, it is thrust x aircraft speed.