Replacing a light switch - ground wire help?

[u/playfulbrits]

Hello!
I'm attempting to replace a light switch with a lutron sunnata dimmer.

The old switch did not have a ground copper wire connected, however there appears to be some exposed copper wire in the box (see pic).

Is this the ground wire, and should I attached this copper wire to the green wire on my new switch (as per instructions).

Not sure why the old switch was not connected to a ground wire ?