How to get ad headlines?
Yes, but didn't fetch all & full
So the different headlines apply to different ad types. If you are using a mix of types in your campaign, you probably have to pull most of the headline dimensions.
Headline applies to Image ads - it shows the image name and size (as it has no headline otherwise to display).
Headline part1 and part 2 applies to the first and second parts of an Expanded Text ad headline.
Short and Long Headline applies to the short and long sections filled out for the headline in a Responsive Display ad.
See the API description of these fields for more information: