From your images, while the overall CPU usage is only 50%, the CPU indicator is showing all four efficiency cores spinning up to approx. 80% (the 4 left bars). This can explain the heating of the efficiency cores and some of that heat will spread to other items.
One item missing in your charts is disk activity. The temp of the SSD indicates there is also a fair amount disk access taking place.
Also, the battery is also charging and that is adding heat to the unit.
Let the batteries charge full overnight and use the Mac as you did when you took the measurements and see if there is a difference. Another thing, disconnect the charger, let the Mac cool down then run on battery to see what temps you get.
Also, present the data @John Galt requested as well.
With that said, I would not worry about the temps unless they get up above 185-190F for a sustained period.
BTW, do you have a plastic shell on the MacBook Air or some other type of covering? If you do, remove it and things will run much cooler since plastic is a good heat insulator and putting one on a laptop is like putting a winter coat on while working in an office or home at 75F.