That the Kelvin timeline is an alternate universe and doesn’t overwrite the prime timeline.
Official canon says it, the movie says it, Abrams and the writers say it, but you continue to assert that it’s not the case even while arguing that official canon trumps everything else in other cases.
All of this, plus you refuse to accept the possibility in general that time travel can create an alternate universe
I do that because the idea doesn’t make sense to me.
(which, might actually the most likely scenario, were time travel to actually exist).
It is? I disagree. I think if time travel were to actually exist, it would work like we see in Harry Potter and the Prisoner of Azkaban.
I think that is also very possible. What certainly is not possible is that time travel would just overwrite an existing timeline, which is what you are suggesting.