Well, the internet essentially was born from scientists displaying their research and papers, linking to other scientist pages, experiment data, and so on. The early internet was essentially a fancy FTP server with a bit of Times New Roman paragraphs in. That's why web-servers were originally called Internet _Information_ Services (IIS). Because it was designed to be essentially an online library.
Then of course commercial, social, political, and many other areas jumped on board. People found out that sales (if you was commercial), views (if you were political or social), and whatever you were aiming for essentially, magically increased if you made your website _look_ better. It's how humans have always worked.
This gave birth to an arms race where the weapon of choice was including increasingly advanced ECMAScript code into your website.
From this the modern web was born. (i'm simplifying a lot here, but that is generally the very quick overview as to how I experienced it over the last 2 decades).