Considering your age, this game is actually pretty decent. There are a lot of issues I will go into more detail on shortly, but there's no doubt that the very basics of a game are all here.
The idea of shooting down meteors to save the dinosaurs sounds interesting, even original. It does raise the question though of why it's called Dino shooter and not Meteor shooter.
Your game page looks really good too. The only criticism I have there is that the screenshots only show the player shooting down meteors. This is problematic because when you play the game . . .
. . . it's not just meteors you have to shoot down, but also aliens on the ground. Honestly, the game is hard enough with just having to shoot the meteors. There also wasn't a difficulty level setting. I'm not sure, but I think the highest score I got was 100 or something.
The graphics are actually pretty good (I'm keeping in mind that this is made by a 14 and 15 year old). I've never made a game with Unity before, but I can tell you that if my first game had these graphics, I'd be pretty happy. The game world actually looks like it would be fun to explore -- except you can't, because you have to fight off the aliens and the meteors and you usually die within 30 seconds.
I would suggest getting rid of the aliens (that honestly look like very bad Minions) and just stick with the meteors. Or, if you still feel that the aliens have to be in the game, make them attack apart from the meteors or in very very small numbers.
I did see the Shop option and thought that was a great addition, but it would honestly take one way too much time to afford even the cheapest upgrade.
Definitely a promising start and I'd be willing to play an updated version in the future!