Rather than splitting this up into awkward pieces, I’m gonna just smoosh a couple questions I’ve been asked into one that gets right to the heart of things:
Yes, it was definitely Jim. (Unless we allow for a perfectly identical twin, but that’s veering into cheesy territory and—more important for the sake of this discussion—would actually make it less likely that Moriarty Prime is still alive. So we won’t worry about that option right now.)
Yes, it was definitely real moving and talking instead of an animation. (Unless we allow for extremely good computer animation where Benedict Cumberbatch did the motion capture, and—I’M KIDDING, OBVIOUSLY. Moving on.)
But no, it was not any kind of proof that Jim’s currently alive.
Let’s maybe take a step back and reframe this with a different example.
Don’t worry about Jim for a minute. Instead, take a look at this Sherlock character:
Now—what do you think? Is she currently alive or dead?