Apps downloaded from app store not working on MacBook - damaged and cannot be opened
Last year a lot of users had the same problem. It was caused by an expired security certificate, there system did not receive a new one yet. 

I know you already tried a lot. But the right order is important:


Delete the apps from your Mac. 
Log out of the Mac App Store (from the menu bar, choose Store > Sign Out).
Reboot your Mac.
Log back in to the App Store (Store > Sign In). 
Download apps again


If this doesn’t help, I have also heard reports that this issue can be solved by temporarily creating a new administrator user account on your Mac.