How to make animated site with navigation?

Here's an example: hollow.org.uk
I have a task to do similar (in functionality/animations) website, which will be animated to move across the screen about 1500(!) images.

I had not experienced with such tasks and do not even know where to start.

There is a known framework three.js (complete with GSAP apparently), there are whole engines with a graphical interface Verge3d or blend4web.

Please advise something on the stack.