Do not underestimate the abilities of a young shepherd in Judea in biblical times. He constantly had to protect his flock of sheep and goats from attacks by brown bears, leopards, and Asian lions, which still roamed the woodlands of the Judean foothills. Failing to do so would have got him in deep trouble with his father, so he had to become very adept at fending off such threats by whatever means possible—including devastating use of his slingshot.
If the Bible were set in a purely desert environment (as it is usually depicted in Western films), it would not likely not have produced stories that Europeans could relate to. But it wasn’t. The landscapes of the Galilee and the Judea-Samaria mountain range west of the watershed were (and are) very similar to those found in southern Europe (Greece, Italy, and Spain).