It depends on the individual and the particular program. Every program uses words like "Intuitive" in their marketing campaign, it just sounds better than "good luck figuring out how to use this".
I would ask what you are trying to accomplish in the end, are you going for a "drop items in a scene and render" or "making everything from scratch yourself" and rendering a final scene. There is a vast difference between the two.
I would also suggest trying all the demo's for programs available to you. You are on a Mac so that shortens the list somewhat already. The interfaces between 3d packages differ allot, if they all worked for everyone they would all look the same
. For a simple intro there are things like Bryce(5.5 is free), Carrara 3d Basics(cheap), Daz Studio(free uses content).
Training courses or video's that are the basics also would help you figure out the lingo for the 3d app you choose.
Do you want to start with a small program and grow out of it or start with a larger program and grow into it? Cost is also an issue with what you have available to you.