"The Cloud" terminology got its start in the 1970's, with telephone network engineers who would design telecom networks on whiteboards. They'd draw one network (say in their city) on the left side of the board, and a destination network (another city) on the right side of the board. All the interesting stuff would be happening in those two places, but they were connected in the real world by a huge network of telephone lines, switches, and other gear, whose details didn't matter to the design discussion.
So they would scribble a loopy oval shape on the board between the cities to represent all that other stuff. It was necessary to acknowledge its presence, but the details didn't matter. That loopy doodle caught on and became a standard way for the telecom engineers to represent "all that stuff in the middle where magic happens and the details don't matter".
It wasn't until a few decades later that some marketing person was watching a design review, and said out loud, "Hey what's that stuff in the middle? It looks like a cloud."
Later as the internet started to grow, the same "magic doodle" came to represent "the place where the magic happens and the details don't matter", the name "The Cloud" spread in usage, and after Amazon got AWS started up in their shopping server farms (a.k.a. "datacenters") in the early 2000's, people's data started living off-site, in "The Cloud".
As they say, "There is no 'Cloud' -- it's just somebody else's computer."
But long before the internet was invented, it was just a doodle in an engineering design on a whiteboard.