Can’t tell by your phrasing here whether you’re aware of this or not, but no use of a Time Turner in canon altered the timeline, either. Everything that Harry and Hermione did while time-turned was exactly what the trio saw the first time through. That part of HPMoR’s time travel rules are identical to canon’s, just more thoroughly explained.
Yes, that’s what the (apparently) was for. The point is that this is a canon example where a character thought someone was dead and used a Time Turner to rescue them, but the timeline ended up working out so that they were never dead in the first place (as it had to).
Can’t tell by your phrasing here whether you’re aware of this or not, but no use of a Time Turner in canon altered the timeline, either. Everything that Harry and Hermione did while time-turned was exactly what the trio saw the first time through. That part of HPMoR’s time travel rules are identical to canon’s, just more thoroughly explained.
Yes, that’s what the (apparently) was for. The point is that this is a canon example where a character thought someone was dead and used a Time Turner to rescue them, but the timeline ended up working out so that they were never dead in the first place (as it had to).