Can I choose to show a campaign only on the homepage?
Yes, of course!
When you are creating your campaign, and after you have selected your objective and outcome go to Build your campaign > Appearance settings. You will see a field called 'Show campaign only on URLs that contain'.
There, you need to type 'homeonly' and press Enter for your campaign to be shown only at the homepage.
Note: Don't forget to press Enter after inserting 'homeonly', for it to become valid.