I think this is heading in the right direction.

Does the protagonist believe that he is the last of his kind? If so, I think that’s important.

As Richiev highlighted, I think it might be good to specify who or what this protagonist is.

I’d consider adding another factor – this girl is lost and she’s trying to find her way home too. If this girl appears in the first act of the film and is a big enough character to effectively provide the story for everything else that happens, then she’s going to be there for the duration so I think she needs to have a goal too. It’s a Buddy Love story.

Maybe (and I kinda like this idea) she spreads fear and he spreads joy. She displays the same characteristics as him but is actually a different species and this could say something about the world we live in today. This could be a nice midpoint or Act II climax reveal.

When he finds a lost girl who seems to be one of his species, a lonely elf who believed he was the last of his kind must find a way to get her home in the hope it will lead him to a family he lost centuries ago.?

They’re both looking for family and he has his own selfish motive intertwined with an altruistic one. I think the bit about him “spreading joy to others” is possibly unnecessary… it tells me a little about his character but I’m not sure it does anything to the plot.

What’s the ending? What’s the message?

Excited to see where this goes next.