Please explain your reasoning.
nobody specified that the parts of the ship would be replaced with the same parts
I point you to the definition of “replace”
Replace : to restore to a former place or position
2: to take the place of especially as a substitute or successor
3: to put something new in the place of
If you take something apart and build something new from it, you aren’t replacing anything, you’re building something. You’ve replaced Theseus’s boat with a wagon.
If you take my grandfather’s axe (I replaced the handle twice and the head once) and whittle it down into a cane, you haven’t replaced the handle you’ve made a cane.
So, using your logic, when you grew up and your body changed over time then you’re no longer the same person?