> I'm fairly certain that a rocket launcher only has one use - blowing things up.

At least, until someone implements rocket jumping.

But back to the matter at hand, dictionary.com agrees that That Word Doesn't Mean What You Think It Means: http://dictionary.reference.com/browse/polyvalent?s=t&path=/

There are better words to pick to get across the concept of "can be used by anyone", such as:
- simple
- easy-to-use
- intuitive