Even if Rey isn’t a Skywalker, she is essentially the heir to that role and the bearer of their legacy. I believe it’s fitting that the end of the Skywalker story would focus on a non-Skywalker who will carry and pass on the torch after they’re gone.
I would use the word “usurper” rather than “heir”.
If you want to talk about a heir, technically it would be Kylo aka Ben Solo who should inherit Anakin’s lightsaber and the Millennium Falcon as birthrights, being the only current surviving member of that family.
Obviously because of his history that will never be allowed to happen but he still has far more right to that legacy than Rey ever will who is essentially a random with a ridiculous affinity for the force who just seems to automatically collect OT character’s iconic belongings as she goes along. It seems at this point that the Falcon is just hers to use as she will, complete with co-pilot Chewie who’s only job it seems now is to just fly her about and she essentially stole Anakin’s lightsaber since Luke never gave her leave to just take it, you could even say it was taken by force if you factor in her pulling the lightsaber on him before leaving. And that’s before you get into her role which does not feel earned in respect to her command of the force or suddenly integral role to the rebellion, but that’s an argument for another thread.
Rey may be the legacy torch bearer Disney needs but not the one we fans deserve.