What is the next step after measuring the bed levels?

My Creality CR-10 Max is equipped with a BL Touch sensor for bed leveling.

The bed size is 450 mm x 450 mm.

Here is the 16 measurement points taken from a 4×4 grid:

float  v[] = {-1.15625, -0.7625, 0.1525, 1.13,    
-1.1150, -0.5150, 0.2125, 1.650,    
-0.8525, -0.215,  0.510, 1.4425,    
-0.4125, 0.2649, 1.0350, 1.9050};

Which looks like this:

The bed doesn’t look flat or level. To what extent should I try to make the bed flat and level?

It’s now a day later, and the bed looks like this (image below) after turning the four knobs using AUX leveling (a helper to locate the nozzle above the knobs), so that the nozzle barely scratches a sheet of paper:

float  v[] = {0.0849, 0.0599, 0.1549, 0.2874,
0.2674, 0.0624, -0.0425, 0.0699,
0.3374, 0.1199,  -0.0150, 0.0199,
0.5399, 0.3349, 0.1899, 0.2074};

I also notice that the bed is slightly concave in its center: using a straight edge (a steel ruler on its side), there is enough room in middle ninth (center square) under the ruler for one sheet of paper.