This is the 1057th most frequent Polish word.
człowiekiem
The Polish word "człowiekiem" means "human" or "person" in its instrumental case form.
Here, 'człowiekiem' is the instrumental case form of 'człowiek' (man/person), indicating the means or companion of the action 'rozmawialiśmy' (we talked).
Rozmawialiśmy z człowiekiem w parku.
We talked with a man in the park.
Here, 'człowiekiem' is the instrumental case form of 'człowiek' (man/person) used after the verb 'być' (to be) to describe Jan as being a good person.
Jan jest dobrym człowiekiem.
Jan is a good person.
In this context, 'człowiekiem' is used to classify or define the type of person someone has become, showing the instrumental case indicating a change in state.