How to escape from an aircraft if the door is not armed?
The door the passengers are loading through is obviously one route, back down the jetway or stairs.

The door being "armed" does not affect whether it can be opened or not.  When the door is armed, opening it will also automatically inflate the escape slide.  When the door is disarmed, the slide will not inflate.

Additionally, each door has a manual inflation handle for the escape slide which the crew can use to deploy the slide if needed.

I could not find a non-copyrighted picture to include.

You could start here for more information.