Not all of your examples actually support "one timeline". Here is the best summation of what I mean that I've found (I didn't write it but I find it makes the most sense--it is not the most "natural" way of viewing the time travel stories in Trek but if one examines them closely enough, it is the most logical).What do you mean? I wasn't arguing whether they were properly fixed 100% or not, I was saying these episodes argue for one timeline, not multiples co-existing. If going back in time didn't effect the future, but instead simply branched off to another, 'parallel' timeline, then there's be no point in doing it.
The only example in that list that features a 'divergent' timeline is Yesterday's Enterprise, and that's debatable. As soon as the time travel incident occurred, we saw the current-day events transform immediately (war with the Klingons, etc). It was only due to Guinan's actions that the timeline (which I believe to be the same one) was restored (another example of a character feeling it's important to 'fix' it).
As for Sela being created as a byproduct, well, I figure that's another one of those 'the time traveler has been protected from changes in the timeline due to the nature of time traveling itself' incidents, like FC or City on the Edge of Forever. And Trek '09.