Christian, no question is a stupid one, that is how we all learn!
Most of us who have been surfing behind a boat for a long time started on "regular" surfboards. They have only been making boat specific boards for a few years now, and people have been "wakesurfing", or as we used to call it, "freeboarding" since I was a kid, (and that's a loooong time ago)
My two sons still actually prefer using their ocean skim boards when riding behind the boat.
Go out and have fun on whatever you can!