You dreamt that you were someone else. And 1920, ooh, interesting dream. I think that's cool. I never dreamt I was someone else, I had some dreams where I wasn't in a time or place that I could have ever reached, but I was still myself, or at least I wasn't at least aware in the dream that I was someone else if that was the case.
I think it would have been scary if you would dream that you are yourself but see someone else in the mirror. Or worse, if the mirror wouldn't copy your moves. That would go directly to the nightmare section. For some reason I haven't had nightmares in a long time. The worst dream I got was dreamed being arrested and I was like "my life is over", I have no idea or don't remember what I was arrested for or whether I was indeed gulty or innocent. But it was a realistic dreams. I had unrealistic dreams but they don't scare me that much, maybe part of me realises they are not real.
I had a dream with a monster once, and I would try to fight it. Everytime the monster would kill me I would wake up from where I started the dream and try to kill the monster again, only to fail and wake up again. This is not like Sisyphus from Greek mythology who was forced to roll that boulder on a hill only to see it fall down when near the top and have to start again, I was actually having fun with this.
But by far the best dreams are the ones where you are self-aware that it's a dream. When I'm like "wait a second, this is a dream?", the first times I became self-aware got too excited and woke up, but after a while I didn't get so exited anymore and managed to calmed down. I usually pinch myself first, if I don't feel anything then slap myself. Comebine that with the fact that everything around you feels weird and it's a dream.
Three things I remember I tried to do when I became self-aware of a dream: fly - really cool, jump of a building - again, really cool, for some reason when I landed I broke the asphalt like Hulk would, make that's how I imagined it would happen in my head, but let's be real, if I tried that in real life the asphalt wouldn't even budge, and crashing the car into a tree - I wanted to see how it feels like, except the pain part because you can't feel pain in a dream, I felt the adrenaline of going towards the tree and the sudden forward push when hitting the tree and that's it, for some reason I was wearing a seat belt, I literally have no idea why because you can't die in a dream. I don't remember exactly, but I think there was a smaller backwards push after the forward initial push as well, it was a long time ago and I could be wrong, but I remember the adrenalie before the crash and forward push clearly.
For some reason there are things you cannot do in a dream even if you try them to, for some reason your brain just blocks you. I don't remember what I was trying to do, I just remember that no matter how hard I tried to make it do, it just won't work, or alternative ways could be found around it, which is a weird thing because normally you have complete control over your self-aware dream.