The answer is simple: their ancestors lived in the Middle East, in desert regions. It is only later that they discovered other places, including the forest and met with cold water. This may explain their distrust of everything aquatic!
Paradoxically, the cat is an excellent swimmer, it is instinctive. But be careful not to leave them alone at the edge of a bathtub, swimming pool or any other water-filled containers. Indeed, cats feel a kind of fascination for everything that is aqueous. They might therefore fall head first and drown from exhaustion.
Water fascinates cats, but it also worries them: what strange behavior!
And if you wonder why your cat can spend hours in front of water flowing from the tap, you might say that it's like television for us, it's fascinating it's constantly changing, it's great!
Cats do not voluntarily go into water: they are not fisherman at heart, and not having access to water until late in their evolution, they do not assimilate to the water from rivers or lakes to food. However, if you put a jar with a fish in front of them, there's a good chance that they will grab and swallow it!
Some breeds are less suspicious: Maine Coon or Siberians in general, forest races, enjoy water more readily. For other races, they must be used as soon as possible to bathing. Start when young, in warm water. Find a place where the ground is not slippery.
Your cat will begin to like it, and even slip into the shower with you!