The last known queen of Naboo was Padmé, who died in childbirth at the end of the Clone Wars. She gave birth to twins, and Luke was born just before his sister Leia.

If the line of inheritance works the same way in the galaxy far, far away as it does in most earthly monarchies, this would leave Luke next in line for the throne.

Is Luke entitled to claim the crown and become King of Naboo?

Note: I'm not asking if he would actually make such a claim, nor am I asking whether the Jedi Code would allow for a Jedi to be a king as well — I'm only interested in the issue of whether Naboo's laws would allow Luke to claim the throne, all other considerations notwithstanding.