Well there's no chance it was a settlement, you couldn't swing a cat in there let alone build a dwelling.

It could have been a defensive enclosure but i'm not totally convinced it was even though the walls might suggest this, it does have defensive "capabilities," though with loads of places to hide, it would be a great site to ambush an enemy if you could lure them up there in the first place but by no stretch of the imagination could you call it a fort.

Ritual enclose, well that explanation is just a stab in the dark despite what the experts might say, there is not one single piece of evidence to back this up unless you know something i don't.
The comparison with Gardoms edge also doesn't sit right with me either, there's a total lack of evidence of anything solid to base assumptions on at Carl walk where there's lots of evidence of activity at Gardoms.
Just my two-penneth as someone who lives quite close to the site and has been up there too many times to count, truth is we'll probably never know.