Did the aborigines become a colony of Captain Cook?

No.
James Cook did not make anyone or anything a colony.
Cook named the east coast of Australia 'New South Wales" and claimed it for England.He later recommended it as suitable for Great Britain to establish a penal colony. He disregarded the indigenous people, declaring the continent 'Terra Nullius', or 'No-man's Land', and free to be colonised. He did not colonise the Aborigines.
No.
James Cook did not make anyone or anything a colony.
Cook named the east coast of Australia 'New South Wales" and claimed it for England.He later recommended it as suitable for Great Britain to establish a penal colony. He disregarded the indigenous people, declaring the continent 'Terra Nullius', or 'No-man's Land', and free to be colonised. He did not colonise the Aborigines.