macOS Mojave Shutdown cause
Yes, a shutdown cause value of 5 means it was a totally normal shutdown.

A "Shutdown cause was a PWROK event" basically means that your system shutdown with no power supply issues - as in PWROK = Power Okay.

A "Shutdown cause was a THRMTRIP# event" basically means that your system shutdown due to a thermal trip - most likely due to overheating - so your Mac shuts down to protect itself from damage.