Sorry, but I still don't think you're right.
In fact, your understanding doesn't sound like anything I've heard from anyone else. The link doesn't give examples of what can be, but what is personal data.
"Personal data is any information that relates to an identified or identifiable living individual. Different pieces of information, which collected together can lead to the identification of a particular person, also constitute personal data."
This says something about the data, and how it relates to a person in itself – not what practical ways you have in a certain context, limited only to other information you have immediately available in that same context. It's about whether the individual is identifiable – the ICO says [0]:
"You should take into account the information you are processing together with all the means reasonably likely to be used by either you or any other person to identify that individual."
Otherwise, this next part wouldn't make sense:
"Personal data that has been de-identified, encrypted or pseudonymised but can be used to re-identify a person remains personal data and falls within the scope of the GDPR."
It isn't an issue of whether you're able to identify the person given only the information you have available – but whether the candidate can be theoretically identified.
[0]: https://ico.org.uk/for-organisations/guide-to-data-protectio...