To come back a moment to the difficulty of visualising how intake and exhaust provided "nearly all" the thrust, and the engine "next to nothing"....
Think a moment of various marine and industrial gas turbines (Olympus and others).
What does the engine do in those installations? It is a 'gas generator', and all the power in the exhaust is extracted by a separate turbine.
As a matter of fact, the thrust of those engines is practically zero, since having thrust in a stationary installation would just be a waste.
On Concorde at Mach 2, the situation is really not all that different...
By sucking a huge amount of air through a very sophisticated inlet, it sets up pressures in that inlet, that provide about 75% of the thrust.
By blowing that same amount of air, with added heat energy from the fuel, out of the other end, through another sophisticated convergent-divergent nozzle, we produce yet more thrust.
The engine itself produces very little thrust, but by 'sucking' and 'blowing' on the right components front and back it creates the right conditions for those components to produce the thrust we're looking for.
I hope this makes some sense?
CJ