Guy Behind Viral A.I. 'The Puerto Rico Song' Says 'I'm Not a Musician'

William Stiteler -- the guy behind the viral 🎶First Time in San Juan🎶 A.I. song blowing up TikTok and Instagram -- says he never expected the goofy Puerto Rico anthem to become an actual hit ... because he doesn’t even consider himself a musician.

Roll the clip ... the creator of the Saxboy Billy account tells TMZ he writes all the lyrics himself, but says the songs were originally just meant to add comedy to his travel videos online.

"I'm not a musician, baby. I'm a slob," he told us. "I don’t claim this to be music."

Stiteler says he's been using A.I. music platform Suno for nearly two years to create campy, catchy songs that help showcase his travels in a funny way ... comparing the tracks to cheesy 1980s sitcom theme music mixed with yacht rock vibes.

He hadn't been putting the songs on Spotify or trying to profit from them because he viewed them as unserious. But once "First Time in San Juan" popped off, he changed his mind.

Stiteler says some British music distributors convinced him the A.I. music wave was inevitable anyway ... basically telling him, “Mate, you knew it was coming.”

The song has since become a social media phenomenon ... with everyone from influencers to celebrities posting lip-sync videos ... with arguably the biggest moment being when Luke Combs belted out his own rendition.

And Stiteler's already thinking bigger ... after boy band O-Town posted a lip-sync to the track ... he says he'd absolutely work with musicians in the future -- especially boy bands.

Ironically, despite the massive success, Stiteler says only one music industry person has reached out ... and the guy was allegedly trying to steal his A.I. prompt.