The character was a naive country farm-boy. These aspects were played up and exaggerated.
Farmers are more "in tune" with natural events, so Walter's ability to perceive the arrival of helicopters (a disturbance in the environment) was an extension of this.
The stereotype of the "country bumpkin" is not without merit. I've had to bail a few countrified cousins out of social blunders they've committed while in downtown Los Angeles.
Another aspect of Walter as the country bumpkin is his lack of previous experience with the ladies. Imagine yourself as a person whose only extensive female contact has been with your mother, your female cousins, and the occasional female classmate who turned her nose up at your farmboy ways. Now imagine yourself suddenly plopped down in the middle of a foreign country, surrounded by attractive, aggressive, and available women of nearly every ethnicity you can imagine, and men who were only too willing to brag about their experiences with them.
No wonder he was so timid.