Even if I was the inventor of this piece of equipment, I would still never tell you it was the only training tool you will ever need to reach your goals (although I do feel it could be ;D) Yes, you could only use it and excel at superhuman levels but I prefer to look at things in a complimentary fashion vs an either or.
The barbell. Definitely my favorite piece of equipment and whether you are a newbie or a seasoned vet, the barbell is hands down one of the best tools for any and all goals.
Barbell training is a great way to get a lot of work done in a short amount of time. There are a ton of exercises you can do that will hit just about every muscle in your body, from the superficial to the stabilizers and if you move the bar at a faster pace, you will work your heart muscle pretty darn effectively too!
Want to be faster, have a firm round booty, jump higher, throw powerful punches, be able to LIVE a long life, not be on a medication timeline, look great nekked from head to toe etcetera etcetera (did I spell that right :p) ? You can do some of the following barbell exercises:
Angled Barbell Press
I could seriously go on forever on not only the variations of these particular exercises, but the countless other exercises and ways to use barbells for any training goal. Maybe these are not fancy new age moves, (and I could show you some in person if you’d like and have some training behind you) but these basics just freaking work. The entertainment exercises are great for just that as well as for advanced peeps.
With even just the above exercises you are going to build fat burning, performance enhancing muscle mass and strength from head to toe, literally.
With the above, you will be preventing a whole host of diseases (and while I guess I am not really supposed to say this but you will most certainly treat or fix some you may already have) and other misfortunes that come from NOT training.
More work done in less time with barbell training no matter your goal, your age or your training background, sounds pretty kick ass to me!