How can I make something like $() that jquery uses?

Think of $() as being a wrapper object that wraps up a lot of functionality.

I will give you an example you can run to see it work.
But this sample will be a bit simpler.

let $ = (el) => {console.log(el)};

That actually defines a function named $ that takes one parameter named el.

To run it you can pass in an element like the following:

$(document.querySelectorAll("img")[0]);

You could make $ an object that contains a bunch of other functions (basically what jQuery did).

let $ = {};

$.double = (a) => a*2;
$.multiply = (a,b) => a*b;

Now you can use it like the following:

$.double(3);
$.multiple(3,4);