The graphics and detail are unquestionably not that great, and not much excuse can be made for them being in such a condition. The audio which doesn't seem to be credited (you might want to) is alright though not really suitable.
On the plus side, the game does work and the leaderboard gives it some competition. It's simple yet effective and with that little bit of competition it makes the game plenty of fun.
One problem though is if you move to the far left you can't be hit and therefore can sit there and rank up points giving yourself top position on the leaderboard; which I did do at 50k points. To fix the problem I would advise moving where the bars can hit just a tad to the left so no one can just go "afk".
A possible glitch, but one that actually works against the glitch I mentioned above is if the window is minimized it seems the score doesn't move up. Therefore you always have to keep the window open if you even want the points to go up.
For 30 minutes, and even though it's not much of an excuse, being the age of 14 and to make this is mildly impressive and shows potential. Keep working at it and spend some more time in your projects and i'm sure you'll be making amazing games in no time flat!