As professional experience is mentioned in almost all job adverts, can I still apply as someone just starting out in their career?

It depends on the wording: words such as ‘ideally’ or ‘desirable’ indicate a non-mandatory requirement, i.e. not an absolute prerequisite. With ‘required’, the situation is different.

‘Initial work experience’ means that you have already had a taste of the working world and that your expertise is not purely theoretical.

Where ‘relevant’ or ‘pertinent’ work experience is specified, however, employers expect applicants to have worked in this field, in the same sector or in a comparable role, and to be familiar with the tasks and processes involved. In other words, you have a direct connection to the job you’re applying for, as well as relevant prior knowledge.