On a day to day basis, I probably use copy-pasting of text at least a couple of dozen times. While selecting/highlighting text using the mouse is quick in most cases, if you have to be precise or need bulk selection, nothing beats keyboard shortcuts. For a handy list of universal shortcuts, check out this article.

I use the combinations listed quite a bit and once you are accustomed to them, you will find it is much faster than using the mouse. After all, you are going to (probably) use the keyboard for Ctrl+C and Ctrl+V anyway, so your hands are already on the keyboard.