Hi there milhouse! Nice to meet you. I find myself dreaming in the third-person a lot, but also in the first-person. It seems to vary.

I wrote this as a response in the lucid dreaming subreddit, but I wanted to cross-post it here with just a little editing. My response was answering why it was harder to visualize in the third-person, but I think the idea partially applies here:

Yes, first-person always seems harder to visualize. I think the reason lies with the "picture" you view while visualizing.

In third-person (e.g. a movie), the "picture" is very smooth. It continues with its rectangular view, and pans and zooms the world, and you see the world and everything in it with smooth transitions, different views, and, most importantly in my position, stillness.

In first-person and living day, our eyes naturally jerk from point A to B to C, and we have one view (e.g. through our eyes at exactly 5'2" height) with shakiness caused by our moving head.

Because first-person is more rigid and strict, whereas third-person has more possibilities, I feel that a lot of the time visualization happens in third-person.
Thinking back on that, I thought of an extension to that reason, but I'm unsure of the validity. Our minds might adjust to third-person to keep us in a sort of dreamy suspension of disbelief, in the same way we can watch a performance on a stage and feel absolutely dismayed at the terribly sad fate of a character, although we know (but have completely forgotten during the scenes) the actors personally. If our dreams seem oddly far-fetched, our dreams might shift to a "dream-like state" of belief in third-person so that we may watch them and not interrupt. In addition, this could even partially account for lack of awareness or our dreamself's acceptance with following the dream plot. If that's confusingly worded, I apologize!

I guess to help answer the above question, I would need to find a correlation between far-fetched & third-person dreams, and then more normal & first-person dreams. Perhaps vividness plays a role in this as well; are the more vivid dreams in first person or third person? This could really be a good topic of interest!