JavaScript Loops, Arrays and Objects! Is this course necessary to actually make websites using JavaScript??

Arrays and other data structures are essential to learning any programming language. I'd be hard-pressed to name a language that doesn't have them. The same goes for loops.

While you might not yet understand the significance, I can promise you that knowing this stuff will help you build a better website. One thing that springs to mind when we talk about visuals for a website and JavaScript is the animation of SVGs. Any knowledge you have of these foundations is just going to give you a larger creative canvas to work with.

For example: here's a simple codepen that I did that's a random quote generator. It also randomizes the color of the text and borders every time you get a new quote. Even doing this simple site requires that I understand key and value pairs. You're welcome to take a look. http://codepen.io/jen-nordell/pen/BjVJra

If you want to build a really basic static website (no AJAX, no API requests etc) then not really. If you want to venture in to things slightly more complex, then yes 100%. Even some user interactions require loops and arrays though so bear this in mind. For example, iterating over buttons to attach a click event handler to.

As the others said, not necessary - you can always use pre-built frameworks, libraries, plugins, etc. However, what if you needed to modify or customize a snippet of Javascript that relied on these to fit your project's needs? You might find yourself "looping" in circles. Having an understanding of the basics and how they work is very powerful ... and liberating!