but Kentucky Thumbpicking emphasizes a bass pattern played with the thumb akin to Piedmont style blues. Thumbpicking is a technique, it's also called finger-picking, fingerstyle, Travis-picking, etc. You can keep time playing bass notes on a guitar using your bare thumb, or a thumbpick like Lester Flat did, or using a flat pick like most guitar players do. What do you mean by thumb picking? Like not using a pick? Study Lester Flatt and his followers, and folk like DelMcCoury. I'm not much of a bluegrass player, but a long-time rhythm acoustic guitar player, and my approach to learning bluegrass on guitar is what I've described above. You can work out a thumbpicking arrangement as well as a flatpicking arrangement. It's a good thing, IMO, to play tunes in more than one style on guitar, though that's not necessarily a bluegrass thing, I like to do it with all kinds of songs. But I think it's a good thing to master thumbpicking for yourself in Lester's style, as well as developing a flatpicking style. If you have an aversion to thumbpicking, I suppose you can forget going to the roots and study people like Del McCoury. Look for any footage of Lester, and look for current players/teachers videos who play in Lester Flatt style. A good place to start is by listening to Lester Flatt. Primary thing about Bluegrass IMO is vocals and rhythm, I'd get a real good grounding in that before worrying much about instrumental breaks. Just my opinion here, best place to start is rhythm - since guitar as a solo instrument came later in Bluegrass.

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