I'm new to speedrun.com, and it seems as though no one really plays the game I play (there being only 1 run of the game). Any tips on how to deal with this?

What do you mean by "deal with this"? If you're hoping that more people will run the game, you're probably out of luck (especially for the DS version of a movie tie-in game). Streaming attempts, creating guides where they may be needed, discovering new tech, all that sort of stuff can help to generate interest and make it easier for anyone who is interested to get into running it, but if nobody wants to run the game, nobody's gonna run it, and there's not really anything you can do about that.

I didn't necessarily mean to say that I want people to run the game, it's just that I wanted to know what I could try to do to improve the game's running info, since I'd tried contacting the WR holder and had no luck. Thank you for the feedback, I'll try to incorporate most of the things you've said.

normally for games it comes down whether or not they have a community to rely on, otherwise the game falls flat and lost with no potential found. my only suggestion is probably formulating strategies on your own, and hope that one day the wr holder will be willing to help and broaden the games information.