The sculptures of Sennacherib show the bare-headed and bare-footed suppliants of Lachish meanly clad before Sennacherib (Ball, p. 192, contrast the warriors with caps and helmets, ib.
The Sherden had been in the armies of Rameses II., and are distinguished by their remarkable helmets and apparently body armour of metal.
Heuzey has pointed out, to one carried by the chief of an Asiatic tribe in a tomb of the 12th dynasty at Beni-Hasan in Egypt), while his kilted followers with helmets on their heads and lances in their hands march behind him.
While helmets provide little protection in a serious fall, they're a must to shield you from junk dropped or dislodged from above you.
Armour and helmets were not generally employed at the time of the Anglo-Norman invasion.