I have an iPhone 5 and since I installed iOS 10 I have to press home button twice to unlock the screen. I hate having to do this. I feel that there is 200% probability more than before that my home button breaks. Is there any other way to unlock the screen? Is it possible to go back to the 'Slide to unlock'? I would also hate to put the Assistive Touch button on the screen.
You can't use Slide to Unlock without jailbreaking. Since your device does not have Touch ID, you can't use Rest to Unlock either, and your device does not support Raise to Wake either.
One way to reduce the wear on your home button is to use the power button to wake the device, then press the home button when you actually wish to unlock the device.