Well, children, where there is so much racket there must be something out of kilter. I think that 'twixt the negroes of the South and the women at the North, all talking about rights, the white men will be in a fix pretty soon. But what's all this here talking about?
Powerful stuff, you'll agree. I can only imagine how much the crowd must have lost their shit on hearing it.
I want to say a few words about this matter. I am a woman’s rights [sic]. I have as much muscle as any man, and can do as much work as any man. I have plowed and reaped and husked and chopped and mowed, and can any man do more than that? I have heard much about the sexes being equal; I can carry as much as any man, and can eat as much too, if I can get it. I am strong as any man that is now.
Of course. It has cadence, and rhythm, and repetition. It has that easy conversational style that only comes from diligent polishing. It is skaldry, without any hint of scolding. Cf Marcus Rediker's discussion of the famous slave ship deck plan, in his book The Slave Ship, prepared by and for abolitionists. Its clarity is a lie - it under-represents actual slave ship crowding and confusion - but it communicates so beautifully that it has remained useful, not just for abolitionist arguments but for anti-capitalist and anti-fascist ones as well.
The more colloquial version serves to underscore Truth's status as Other--but thereby also strengthens her position as the embodiment of, and spokesperson for, all the women who fell outside the cracks of the chivalrous patriarchal definition of Ladyhood.
As bemused_leftist points out, a lot has to do with to what extent Truth herself consented to the edit.
That's a great speech - or maybe two great speeches. You're probably right that the rewrite makes the oratory more powerful. But the 'original' has a wonderful dignity ('original' in quotes because this isn't the speaker's own draft, is it, it's someone's record of the speech, hence that garble of 'I am a woman's rights').
What makes me uneasy about the rewrite is that it plays up the idea of the speaker as uneducated, simple: "they talk about this thing in the head; what's this they call it?" I suspect that the use of the form 'ain't' had a shock value that we can't really feel. And yes, it makes for a powerful effect, and gives the speech a power for good - but at a price.
The 'original' version (if correct) was delivered with voice and gestures and audience reaction. Lacking those, the re-written version may have needed to add rhetorical flourishes for print distribution.
I'd wonder if Soujourner was consulted during the re-write?