Most of the giants cannot eat an adult human. A 180 lb retic or burm can't eat a 180 lb adult human. Now if you put a hungry one with a human infant or small child all bets are off. But generally, a human adult is too big to be a prey animal. It could in theory happen sometimes with a really big snake (and I mean big for the species--a 200 lb one) with a smallish human (for instance, a friend of mine is 5'2" and maybe 140--he might be a doable if very large meal for a 200 lb python). But it's not typical.

And I can vouch, first hand, snakes will apparently do constriction as a form of self defense (although I don't know how to empirically test their motives)
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We wouldn't have 6 and a half billion people if you had to be beautiful to get laid.
1.3 African House Snakes
3.2 reticulated pythons
1 corn snake
4.3 Florida Kings
2 speckled kings
1.2 ball pythons
1 Argentine boa
1 Texas Rat Snake
1 checkered garter snake