I am trying to implement this effect
inside a wordpress page:

There is a plugin that will implement the supersized effect, but it only applies to the entire body bg. I found this implementation through a forum post (on another forum somewhere) of how it can be applied to a specifically sized div. As you can see, the effect works in a standalone html file. I linked the same exact scripts and placed the css on the wp page itself with the html from the sample file (not published in wp btw), but am not getting the images to show up. Any ideas on what I need to focus on to fix? tia.

unfortunately in wordpress either your css or javascript is conflicting with another plugin. it's a simple case of trial and error removing other plugins you have to see which is causing the issue then drilling down to find the problem.

Unfortunatley you need specialist knowledge if it is a javascript conflict. most of the time setting jquery.no.conflict resolves the issues but can't be guaranteed.