Permissions denied while trying simple copy and paste

You are logged in as an account with root permissions available, but not enabled.

You can enable the permissions if you need, normally via the sudo command.

However, the sudo command is dangerous - there are no protections left once you run it. If you tell it to delete everything by mistake, it will.

To copy the files graphically, run this:

sudo -i nautilus /home/$USER

And move them to where they need to be. To copy with the command line use this:

cp "/current/location" "/new/location"

I'm assuming that by root you meant your account. root is a separate account which has the highest level privileges. You can switch to root by doing su. However, the preferred choice is to use the sudo command which is much less dangerous.

If you have some experience with terminal, try

sudo cp <origin> <destination> 

Else open the terminal and type

sudo -H nautilus 

This will open a file explorer with root privileges.

16.04 appears to have a problem with running nautilus from the terminal under sudo. Installing nautilus-admin is a great workaround for that.