It's not total, but nearly so. People show a widespread, unusually fast fear response to snakes.
Anecdotally, it seems that this is somewhat less in people who, like myself, grew up in an area without poisonous snakes, but the fear or aversion to snakes remains strong.
If you believe in evolution as the origin of humanity, it could be because our species, and the primates before us, spent millions of years under threat from venomous snakes.
Because venomous snakes were a major cause of injury and death among early primates and human ancestors, those who quickly detected snakes were more likely to survive and pass on their genes.
Primates evolve specialized visual sensitivity to snakes or even snake shapes, allowing for extremely rapid threat recognition.
From a little bit of research, I've found that people do show stronger autonomic responses (sweating, heart rate spikes) to venomous snakes than to harmless ones, but nearly everyone, including those who do not identify as being afraid of snakes, will demonstrate these responses even to harmless snakes. People show stronger responses to snakes than to modern threats like guns, perhaps because, as a species, we've dealt with threats from snakes longer than we have guns. This would correspond with additional data indicating that people have stronger autonomic responses to knives than to guns. As a species, we have dealt with threats from knives far longer than from guns.
People who grow up without venomous snakes often dislike them and will be startled when suddenly confronted with a harmless snake.
People in regions without venomous snakes often show less intense aversion, but the aversion doesn't disappear because the evolutionary predisposition remains, and the visual cues of snakes still trigger the fear center in our brain, even in people who claim not to be afraid of snakes.
Even among people with little or no experience with snake species, venomous species elicit stronger physiological fear responses than nonvenomous ones, suggesting that our brains can discriminate danger levels automatically. This isn't true in all venomous snake species, but it is in most.
Across cultures, snakes are often portrayed as evil, deceptive, dangerous, aggressive, mysterious, or untrustworthy.
Abrahamic religious traditions portray the serpent as evil and responsible, in part, for mankind's banishment from Eden, but that theme carries through to other parts of Scripture, including Christ stomping on the head of a snake.
Regardless of traditions, snakes are almost never neutral. They are either tempters, tricksters, destroyers, or guardians of forbidden knowledge.
This is seen not only in the Eden story but also in Greek, Mesopotamian, and Hindu myths. Quetzalcoatl, in Mesoamerican traditions, is portrayed as benevolent but still powerful, mysterious, and otherworldly. Even when the snake is portrayed positively, it's never mundane.
Cultures without venomous snakes still develop snake-as-evil stories, while cultures with venomous snakes often develop snake-as-sacred myths.
In Christian traditions, the serpent is the first deceiver, the creature that introduces doubt, temptation, and disobedience. The curse in Genesis (on your belly you shall go) frames the snake as permanently degraded and opposed to humanity. In later Christian interpretation, it became associated with Satan. Christ crushing the serpent's head becomes a symbol of triumph over evil.
