You are currently confused on why your attacks are doing no damage and why the boulder does 999 damage by simply rolling over.

I can list a few factors, such as (1) That sword of yours is almost broken (2) boulders aren't affected by swords that are on the brink of collapsing, and (3) you are just really, really weak.

You are most probably thinking about the fact that you can survive these 999 damage attacks, and my anwser is most likely because the last page literally says "interactive animation page" and not "interactive game page" so there is no clear working health bar. Just keep in mind that you'll see more stuff like this in the future, so grab a family size bag of chips and put on some diapers in case you crap yourself, okay?