I really like the speedrun theme and the idea behind the game! I think it could become even more interesting with a bit more variety, though. For example, having more levels, different difficulty settings, or some kind of randomness between runs could add a lot of replayability to the main gameplay. Just a suggestion, of course! ^^
I also had a little trouble figuring out how to play at first, and I wasn’t sure what the “Z” button was supposed to do. I noticed the controls mention 2 players as well, but I couldn’t see or control the second player. Maybe adding a small “How to Play” section on the game page could help new players understand the controls and mechanics more easily.
I’m also not sure if this is intended or a bug, but when I reach the objective, the screen turns black. If I try to move afterwards, the game starts again from the beginning. If this is meant to be the winning screen, it might be nice to show your previous speedrun times there, along with your current time, so you can easily see whether you improved without having to remember your previous record. Of course, I’m not sure if the black screen is intended to work this way, so take this just as a suggestion!
Despite these little things, I think it’s a really fun little game to play with friends and see who can get the fastest time. With a bit more variety and polish, I think it could be even more fun! Great job! :D