I think the Bootsy connection is over-stated, actually. He was only with Brown for 11 months, and while there were a handful of key singles cut (including Sex Machine), the associate was really quite brief and didn't result in that many recordings.

If you look at the recording from late 1969 and early 1970, like Mother Popcorn, Ain't It Funky Now, Say It Loud (I'm Black and I'm Proud), the direction to harder funk was already very apparent.

This is to say nothing of, say, what Larry Grapham was doing with the Family Stone circa '68-'69, or other west coast funk pioneers.