didn't see this part above

as said, put a math node, and value1 plug in the map, but enter value 2.0 for it, and value2 put 1.0, and set subtract, this will make your map range -1.0 to +1.0, rather than -0.5 to +0.5, just making it easier in some cases to set strength of displacement, such as a 2nd map that you might add ranging just 0.0 to 1.0

it will give your map the range of having -1 (black) lowest depression
to 0 (grey) being unchanged , to 1 (white) highest bump