Yet Williams was nearly one of rugby's great unfulfilled talents as he turned his back on the sport in favour of football for several years after being told he was too small.
It was a triumphant return to rugby in his late teens with Amman United RFC that set the Welsh flyer on course for one of the most remarkable careers in modern rugby.
Williams, now 38, is no stranger to such impressive feats, making Lions history when he equalled a single-game scoring record with five tries against Manawatu on the 2005 New Zealand tour.
And despite Williams' rapid rise to stardom, the Glanamman boy has retained strong links with his first club and continues to be an important presence around the side, according to Amman United chairman Darrel Campbell.
"Shane was very small for his age and a coach at his school basically told him he was too small so he lost interest in rugby for a few of years," he said.
"He then came back when he was about 17 and within a year he was in our first team and in that first year he scored a club record number of tries.
"He was a gymnast when he was younger and some of the tries he scored for Wales and the Lions showed that agility he had developed.
"Shane still lives in the village and his sister and brother are involved with the club. His brother plays for the first XV at the moment and Shane sometimes turns out for us whenever he's back.
Amman formed in 1903 and has a long history of producing Welsh internationals but the only Lion prior to Williams was flanker Trevor Evans, who toured New Zealand in 1977.
The first XV play in WRU Division 1 West, with the club also boasting a competitive second XV and a thriving colts section that Campbell believes is testament to Williams' influence.
And while the winger's career may have now finished after a spell with Mitsubishi Dynaboars in Japan, Campbell is confident Williams' legacy will be felt across Wales for years to come.
"What Shane has done for Wales and the Lions is exceptional," he added. "There tends to be a thought that size matters in Welsh rugby but thankfully Shane broke that mould.
"Young players can aspire to follow in his footsteps and he's great when he comes back round the club and is just one of the boys.
"He's still out in Japan at the moment but I'll expect he'll be back just after or around Christmas.
"Whenever Shane played for Wales the club would be crammed as people wanted to be at the club where it
started to watch him play. He's encouraged lots of youngsters to get involved."
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