There's no last Jedi. The final scene of the movie explains that there will always be Jedi masters in the galaxy. In the last scene, the little boy after getting scolded by his master, goes off to sweep the stables while gazing out into the galaxy. He fetched his broom, which was a short distance away, by telepathy. That Jedi feat was right at the end of the movie and lasted about a second.
That same boy appeared earlier in the movie in an obscure role. Nobody suspected that he had Jedi powers.