My shoulders are not level with each other - one is lower or higher depending on which one is the normal one ..I never focused on figuring that part out.
I did notice my mom's shoulders are the same way - she fell off the front of a horse drawn sled and got run over by the sled rails. luckily there was a low spot she fell into and it just tore her dress off - she was 12 then.

I did land on my head as a teenager - my horse bucked me off.
Looking back on things I think that was a factor in me getting a bit crooked - my c1 /c2 probably got misaligned way back then , I did have a moderate concussion was "out" for awhile too.

Probably contributed to my c spine "spurs/osteophytes" a bit too.

But I never had any sort of issues or problems until after many yrs of assembly work & hitting age 38.