Even if one believes in past lives and do-overs, (for whatever reason,) the vast majority of you are on your first life.

There are more people alive today than have ever lived and died. Regression dreams (as you put it) are far more likely to be a combination of normal dreaming combined with knowledge gained through reading history and reading or watching historical dramas.

Even regression dreaming (merely back to our own childhoods,) is largely discounted as being unreliable accounts of what happened to us as we grew up. Too much is colored by recent behavior and such dreams can even be unduly influenced by the person assisting in the directed dreaming.

I'd chalk it up to the fever and just enjoy the story your mind generated.