You generally decide how to narrate a story largely for reasons of tone and market, not reasons of plot. So, none of the details of your book that you have listed in your question are relevant to an answer. There is only one exception to the plot-narration rule that I am aware of: If your plot is strongly linked to your tone (such as a work of suspense, or horror) then changing your narrator and/or your point of view can drastically change the effectiveness of your scenes and plot by shifting the levels of suspense up or down. But you are still ultimately picking this because of the tone you are after.
- If you're keeping a secret, then picking a narrator who will be revealed to be one of the characters in the story may cause a reveal to happen.
- If the suspense comes from knowing that everyone is out to get everyone else, you might pick 3rd person omniscient and illustrate to the reader every single person's thoughts and motivations, as was done in Dune.
- If the suspense comes from not knowing enough, then you might pick 1st person or 3rd person close so that the reader only knows as much as the character does at any given time.
- Or, you might play a bunch of tricks and use all of the above if you are a master; see N.K. Jemmison's Broken Earth trilogy which expertly manipulates narration and POV.
However, if you have no good reason for picking a specific narration style or POV, then you should just do whatever the industry is doing. For YA you should pick first person narration because that's what sells right now. For sci-fi/fantasy the default should be 3rd person, close. If you can think of a mitigating circumstance, something special about your particular story, then by all means diverge from the norm; but be prepared to put in a lot of work to excel as you will be fighting a tide.
Basically, I can't answer this directly for you because we don't know the right types of things about your book. I suspect, 3rd person omnicient or close is right based on what you've described. But with the right application of skill literally any narration style could work.