There is absolutely no chance of pulling on the prop will hurt anything, with one exception: don't pull at the tip of the prop. If you do, the prop will act like a lever and give you a mechanical advantage that will put a huge force near the hub that might damage it.
Stop and think about it for a second, what pulls the airplane through the air? The propeller obviously. It's designed to take a lot of pulling force, but not a whole lot of sideways force, so try and minimize that by pulling close to the hub with both hands.
Also, thinking that using your hands will damage the prop itself is not correct. Have you ever smashed your head on one? Ask a line guy who has been on the job for anytime longer than a month how hard those props are. Even the wooden ones. The only way you will hurt it is if you beat it with a hammer.
They do jack airplanes by the wings, but you'd had better know the proper area to do it. Otherwise you will punch the jack through the sheet metal. The point is almost always right under the wing spar.