I'm trying to complete some passages of my WordPress development path?

I have problems with some concepts regarding WordPress and its development, if someone could clarify things for me, it would be great!

I understand PHP classes and I know how to generate and use WordPress custom publication types. Do CPT objects belong to a class?

The reason I ask is; if I create a new custom publication type and use functions like get_the_author () on my custom publication type, the functions work while I did not necessarily set the author when configuring the CPT .

I guess it's because it's about the post object and that the author is a property defined by an opener when ALL post types are created? but that's where my understanding collapses a bit.

If someone is kind enough to help me to join points, it would be great, thank you.

Thank you in advance.