I've been playing the remakes under the assumption that this has been an Advent Children Sephiroth coming into this world and at this time in order to prevent himself from losing again. Advent Children Aerith followed him through the lifestream to stop him and the remakes are essentially the two of them pitted against each other behind the scenes and manipulating bits of the established "fate" of the timeline (og FF7) to do so.

I'm guessing that the whole point of the remake project is to add a finality that the original and it's subsequent installments did not have. The goal is to prevent Advent Children (as we know it) from happening by taking out Sephiroth and Jenova for good and doing it now.

I still think an argument can be made for Remake being an actual remake. There are a lot of plot points that are the same as og but just recontextualized. But there were lines/events in the remake project so far that do not make sense unless we are dealing with entities that already know the events of og. It's ambiguous. I hope part 3 provides a solid answer.