I don't know, but I'm still inclined to go with your original impression. When you talk about "roots" you're talking about earliest influences. No doubt, as though Wikipedia article notes, there were also western influences, but influences aren't roots.
Just my humble opinion.
Whenever someone mentions Glenn Campbell, I can't help but think that he was a part of the original Wrecking Crew. He was an extraordinarily talented sessions musician who did not read music, but eventually grew into the artist that we all know.
Glenn was on OG ragin' against the machine. Rinestone Cowboy? Legendary eye poke at commercializaiton and the trappings of fame.
I've been walkin' these streets so long
Singin' the same old song
I know every crack in these dirty sidewalks of Broadway
Where hustle's the name of the game
And nice guys get washed away like the snow in the rain
There's been a load of compromising
On the road to my horizon
But I'm gonna be where the lights are shinin' on me
Like a rhinestone cowboy
Riding out on a horse in a star-spangled rodeo
Like a rhinestone cowboy
Getting cards and letters from people I don't even know
And offers comin' over the phone
Well, I really don't mind the rain
And the smile can hide all the pain
But you're down when you're ridin' the train that's takin' the long way
And I dream of the things I'll do
With a subway token and a dollar tucked inside my shoe
There'll be a load of compromisin'
On the road to my horizon
But I'm gonna be where the lights are shinin' on me
Like a rhinestone cowboy
Riding out on a horse in a star-spangled rodeo
Rhinestone cowboy
Gettin' cards and letters from people I don't even know
And offers comin' over the phone
Like a rhinestone cowboy
Riding out on a horse in a star-spangled rodeo
Like a rhinestone cowboy
Gettin' cards and letters from people I don't even know
Like a rhinestone cowboy