Is your gaming not performing well in some way?
Or, are you just interested in understanding the statistics you see?
It is normal, even desirable to have cpu and gpu utilization be less than 100%
If a resource is used 100% it indicates a bottleneck.
On the cpu, much of the game will run in the single master thread.
On, for example, a cpu with 12 processing threads might show only 8% average cpu utilization if that one thread was all that was running.
An extreme example... yes.
It is the cpu that generated display frames.
On the task manager view, Right click on the cpu display and select logical processor view.
It will give you some insight on how the game processing is spread out among available threads.
As an experiment, lower your graphics resolution and game settings.
If you see a nice boost in fps, then your cpu is capable of running a stronger graphics card.
OTOH, if you see little difference, your cpu is holding you back.