I don’t think you need any riding experience going in, that said not everyone from my class made it. 4 people quit and a 5th person was kicked off the course due to wrecking into someone and generally not absorbing any of the information that was being given to him. The other 19 of us did fine though.
The beginner course is great but they only really scratch the surface. When they gave us our certificates of completion they told us that it qualified us to ride around an empty parking lot at low speeds, as this was all that we did in class. It does build up your confidence and the exercises are there to prepare you for real world riding even if the situations are imaginary and at 15 mph.
“I am the best I am at what I do, and what I do ain’t nice.”-Wolverine