First of all, this template is kind of boring, compared with some 404 templates already approved for sale on ThemeForest.
For a simple 404 Page template the loading speed is so slow, and your document is huge:
In your template’s landing page, there are 9x different variants. But you only changed the background type, which does not show too much creativity. I would invest time in 2-3x different variants (in terms of typography/fonts/animations etc) rather than 9x boring variants (Sorry for this)
In order to be considered acceptable, I would do the changes explained in my points above.