I first realized that dolphins help humans in 1990. I was on the island of Santorini, at an old ruin there called Akrotiri. As I recall, I was stunned to stand in front of a wall painting that contained the image of a dolphin with a small human — as if it was carrying the human? — through the sea. Just now I googled and couldn’t find that image. Here’s one that’s famous from that site.
Meanwhile, there are lots of stories about dolphins helping humans. Here’s one that’s current.