I always thought it was parallels between the ST characters with the OT main characters, where on face level it appears they are echoes of one of the originals, but then it turns out they are echoes of another one. (Insert "Like Poetry it rhymes" image here.)
Rey: Initially think she's the Leia Equivalent, actually the Luke Equivalent
Poe: Initially think he's the Han Equivalent, actually the Leia Equivalent
Finn: Initially think he's the Luke Equivalent, actually the Han Equivalent
You can even see it with their character interactions with who they interact with the most during the films.
Unfortunately going from main character Luke to side character Han is a big downgrade for Finn.
Not helped by TROS not really giving him anything to do at all. The one big thing he wanted to tell Rey gets told in the Lego Star Wars Holiday Special instead.
If we do get some adjacent tv series to the Sequel Trilogy, I hope Finn is one of the first to get one focused around him.
I only saw TFA, but Rey was both Luke and Leia. She was the person that the others went to rescue on the Death Star.
Poe was a nobody.