Alan Baker wrote:

It's true that the exhaust stream doesn't directly push on the inner
surface of a rocket engine.

Yeah, I like that aerospike design, the inside-out nozzle thing.

wing encounters some unmoving air, and the wing then throws the air
downwards, the velocity of the air has been changed, and the wing
will experience an upwards reaction force. At the same time, a
downwash- flow is created.

The wing, remember, is moving forward. "Downwards" is one component of
circulation.