That's the way it's supposed to be—my PC is currently using 35% of my 16GB with 4 apps open plus various normal background processes—security, schedulers etc—and ~15 browser tabs.
16GB is loads of RAM for almost all users, you can relax knowing RAM won't bottleneck your system anytime soon. An advantage of having extra RAM is it reduces 'swapping', where Windows 'swaps' data out of RAM into your HD 'swapfile', which can slow operations quite a bit.
That's how it should be, lol. Don't worry. Your ram will have separate portions. Each portion serves a certain function. The rest of the ram you have will be used for your tasks.