Aluminium does not burn in a shipboard fire, it melts. While Sheffield and Coventry were lost, Glasgow and Nottingham survived significant damage. There always a bit of luck, good or bad, in such situations - where the hit occurs, who and what it takes out, that sort of thing. But the 42s were reasonably survivable ships, particularly after the SA when some WW2 lessons (smoke boundaries etc) which had been forgotten were relearned.
21s were another story; designed to be cheap and fast to build and cheap to operate. Not in the same class.
The lessons of WW2 are all still appropriate. They are about the controlling and preventing the spread of flood and fire, retaining electrical power and the like. Nothing to do with armour or, really, the purpose (other than to be a survivable example of her type) to do with the particular role of the ship. It’s certainly got nothing to do with whether the ship is armoured or not. Although, BTW, many modern surface combatants do have armour - but of Kevlar, not steel.
Oh, and modern warships sides are not the thickness of a Corolla; most DD size ships have plating thicknesses of between about 30 and 60 mm of special steels
