Dolphins are
important to humans because we are still looking and researching our origins in the animal kingdom.
There are several similarities between dolphins and humans that are not even found between humans and apes.
Such similarities gave birth to the theory of the aquatic ape back in the 60's which suggest that some of the
characteristics that make humans different than apes appeared because humans had a semi-aquatic phase long time
ago.
You can read more about this in:
www.paulapeterson.com/dolphin_human_connection.html
The intelligence of the dolphin and the research of it is another important issue that humans care.