Does Marty McFly Actually Die in Back to the Future?

I stumbled upon a video by "That Film Theory" about Back to the Future and it really got me thinking about the timeline of events from the first movie to the third. There were multiple times where Doc came out of nowhere to save Marty.

Previously I would have just assumed it was a "Deus ex machina" plot device. Where essentially characters get out of a seemingly impossible situation for no apparent reason or with no real explanation. Some miracle of coincidence saves the day... However, this video got me thinking about the movie series in a whole new way.

Maybe Doc used the time machine to prevent Marty from dying multiple times, in the same way Marty did for him. If that were the case, how many times did Marty die?