Nah, you aren’t dumb..just don’t have all the knowledge of this business...yet.
This guy likes capable people...and I’m quite sure you are very capable. While you might not have all the knowledge required, I’d be willing to bet with some good guidance and direction you would be like a bulldog on a rabbit, getting it done.
I would always seriously consider someone like you on my team. I value capability and drive over absolute knowledge...hands down.