Buying a CD isn't purchasing a license. It's purchasing a physical product. (I used to run a record label so I know a bit about this.) You actually have more rights when purchasing a physical product (IMHO) - such as you are guaranteed the right to resell the physical product (First Sale Doctrine).
However, you are limited in other ways. For example, you are not allowed to distribute a copy of a copyrighted work, even one you purchased a physical copy of. I believe you can legally make a copy of a physical copy that you purchased - for yourself. However, you are NOT allowed to sell your physical copy you purchased and keep your copy. So, it's okay to make a backup of a CD. But not okay to copy the CD then sell it to someone and keep the copy.
Also, since, like I said, you didn't buy a license, your purchase of that physical copy doesn't give you any right to download anything from anyone... you have the right of ownership of the physical copy you bought.
This is my understanding, based on my previous business experience... I am not a lawyer, so I am sure I am a little off, but hopefully that gives you an idea of how the law generally works with physical copies. Also, everyone ignores all these rules these days, of course, and very few people buy physical copies anyway... so I imagine these laws will be updated in a few years, as they really don't reflect the reality of how people use media today.