My Macbook 7.1 (Macbook white mid-2010) 10gb ram, 250gb SSD Samsung 850 EVO overheats with few apps open
Without seeing your Activity Monitor, it's tough to say what your CPU is doing.  However, a 24 degree temp swing in a couple of seconds is a lot.  

Have you tried AHT (Apple Hardware Test)?

https://support.apple.com/en-us/HT201257

My thinking is that you may have a bad temperature sensor (or it's getting bad info).

If that's the case, there are folks who repair things like this, or it just may be a good reason to upgrade your Mac.  There is a guy in NY that does really good work (I am not affiliated) repairing these boards:  https://mailin.repair/