This would seem the most logical to me as well - time being viewed not as a line, but a plane (or even a 3d space), where attempts to alter "the past" put you i

This would seem the most logical to me as well - time being viewed not as a line, but a plane (or even a 3d space), where attempts to alter "the past" put you in a distinct branch of the timeline (a different spacetime). Of course, this isn't as romantic or digestible as time-travel as envisioned in most fiction (BttF).