Relax. Just remember you're more safe out there in your tent than you are in your car driving to the trail head. Those noises are 99.99999% leaves, small animals or your own ground cloth.

I would venture to say that if you were out there for a couple of weeks you would be sleeping soundly by the third night or so as you adapt to the silence of the woods.

Try sleeping near running water. It's white noise that blocks out all the little bumps in the night. Works for me when I'm alone.