This is sadly most likely stowaways that either fell off ships, or more horrifyingly, have been possibly tossed overboard after being discovered by crew.

The feet, being encased in a floatable material — shoes — eventually detach and float to shore.

"A known woman's left foot, in a shoe that was found floating in the Fraser River in Richmond.[11] The shoe was described as a small New Balance running shoe, possibly a woman's shoe.[27] A forensic DNA profiling analysis indicated that it was a genetic match to the foot discovered on May 22 on Kirkland Island.[32]"

So at least two feet are from the same person. I'm not saying this isn't horrible, but the headline of "20 feet" would suggest 20 different people.