what a deep philosophical question.
On the "real meaning of words" level: człowiek is human being , osoba is person- in fictional world you include elves, dwarves,hobbits etc, in religion you include angels, devils, God(s) on the more casual level : a person of unknown gender is usually referred to as "osoba".
when counting people with numbers we more often use "osoby", when talking about people in general, or using words like "many" we use "ludzie".
the fact that a person is human is refered to as "człowiek.
One can talk about themselves using "człowiek" ="one".
"Człowiek" is not exclusive to male people, but in some sentences we would use "człowiek" to talk about a man , and " kobieta" to talk about a woman.
If you want to get technical:
- „Osoba” – sentient being
- „Człowiek” – member of Homo sapiens sapiens species(or at least Homo genus)
You can find quite a lot of uses of „osoba” for dolphins in google, for example, especially since India declared them 'non-human persons' in 2014.