You won't get an accurate answer to the question of Zimdancehall's history. It's all a matter of individuals claiming to be trailblazers of the genre yet their assertions can't be traced beyond a reasonable doubt.
And back in the day when Urban Grooves was mainstream music in Zimbabwe, there was no such thing as Zimdancehall like it is today, although certain Zim artists imitated the sound of Jamaican Dancehall music.