"I am an adult human."
Translation:Jestem dorosłym człowiekiem.
Yes, but if you can also say you are an adult person. (also applies to men and women) - Jestem dorosłą osobą. or you are an adult woman. Jestem dorosłą kobietą
and you always can say -I am adult. Jestem dorosła/ dorosły.
I am an adult Polish woman and I am not sure if I would say "jestem dorosłym człowiekiem" without context that really rules out other options.
That's interesting because I tried "Jestem dorosła" the second time and it said I had a 'typo'. Ugh typical they haven't added the female forms yet.
In this sentence only "jestem dorosłym człowiekiem" is correct.
But some feminine forms may be missing. English for Polish speakers still has many "typos" like that. I think typos are more difficult to report, and then to be corrected.
you can but you shouldn't unless you know why you want to. It does happen in literature but sounds strange/uncommon, maybe as a part of lecture to 18 yo acting irresponsible or sth.