Shadow line on all my photos with Canon 70D

It looks like a hair in front of your shutter curtains, possibly from a camel's hair brush like the kind used to clean dust in cameras or similar. Your sensor is not visible in the second photo because the shutter curtain is closed and covering it up.

When the shutter curtain is open, here's what a Canon APS-C sensor looks like:

Because the hair is an appreciable distance in front of the actual sensor, it will show up more when you use a narrower aperture (higher f-number) and less when you use a wider aperture (lower f-number). Since what you are actually seeing in your images is the shadow of the hair falling onto the sensor, it will also show up more in lighter areas of a scene than in darker areas of a scene.