yeah I'm gonna retract this, mermaids would probably have a lot more presence if this was the case, and considering ruto and mipha had crushes on their links, sounds like it's not too unusual for zoras to want to get together with a hylian
there's not enough mermaid presence in the series to really tell, but if I had to guess, maybe in universe a mermaid is what happens when a zora and human/hylian have a kid?