Disney and modern culture have done a disservice to mermaids. They are more traditionally portrayed as malevolent sirens, using their beauty to lure sailors to a watery grave. This painting was an effort to restore their dangerous status.
Also, I have another pet peeve with the idea of a half fish, half human creature: you can’t mix a cold-blooded body with a warm-blooded one! Mixing a warm-blooded sea mammal with a human body is much more plausible.
I like the idea that merpeople could be off on an evolutionary branch of humanity from an early, more aquatic cousin that developed along the lines of the land mammals that became dolphins.