I wish I could track down the original source, but there was a theory floating around years ago suggesting that Zeus had relationships with many women as a way to integrate local gods into the broader Greek pantheon.
In Greek mythology, immortality and immortality work a bit like co-dominant traits. When two mortals have a child, the baby is always mortal. When two immortals have a child, the baby is always immortal. But when a mortal and an immortal have a child, that child is a mortal who is greater than any ordinary mortal, often called a hero.
So, picture early Greeks moving into a region where the main deity is someone like Bob. They could either try to eliminate Bob’s worship, let it coexist with their own beliefs, or integrate it into their mythology. To do the latter, they might create a story like, "Oh, Bob! I know him! He's actually a great hero in our mythology too! You see, Zeus visited his mother in the form of a..." and so on.
It's an intriguing theory, but it's tough to find solid evidence. Plus, it doesn’t account for later blending practices with other cults, like the cult of Isis. So, for now, it remains just a theory.