Even though Regroover is quite versatile, as a beat-making tool, it has been optimised for percussive loops. In the background, Regroover’s algorithm searches and finds common sonic and rhythmic elements and groups them as layers.
Of course, nothing should stop you from trying, and you may indeed get very interesting results.
Some users have gone so far as to try and extract grooves from washing machine recordings!
So to sum up, Regroover is best used for percussive loops, but feel free to try it on anything.