Is my understanding of subsonic inlets correct?
Your understanding is correct.

However, you attribute too much activity to what is essentially a passive device. The inlet only guides the air such that it flows uniformly, without separation and at the desired angle towards the fan and the compressor. The pressure field resulting from this flow is doing the acceleration rsp. deceleration, and the pressure itself is a result of the compressor swallowing just as much air as it needs.

Converging streamlines indicate a pressure drop and acceleration, and diverging streamlines a pressure increase and deceleration. In the static condition, the engine creates suction inside the intake which causes air from all around to flow towards the intake. At high speed it cannot swallow more than a fraction of the air flowing towards it and partially blocks the flow through the nacelle. As a consequence, air gets pushed to the sides and the flow into the intake is decelerated.

It is really the engine, not the intake, that controls how much air is ingested. The intake only makes sure that this happens in an orderly fashion without separation and vorticity. Different flight speeds only mean that the pressure ahead of the compressor changes, while the speed of the air entering it is quite constant over flight speed.