Since the film is a classic, availability fluctuates. However, these are your best bets:
Movierulz is not a single website. It is a hydra-headed network of mirror sites and domains. Here is how the "work" of Movierulz functions: bangara s o bangarada manushya kannada movierulz work
Dr. Rajkumar was not just an actor; he was a cultural icon. His films were produced with hard-earned money. Even today, the rights to Bangarada Manushya are owned by his family (the Late Dr. Rajkumar Trust). Since the film is a classic, availability fluctuates
In India, under the Cinematograph Act, 1952 and the Copyright Act, 1957, downloading or streaming copyrighted content without a license is illegal. Since the film is a classic