As a first game, i don't think you've learned much... Only walking, jumping, some menus and stuff, but ok...
The double jump is an infinite jump, and the coins don't reset when you die...
Also the colliders are pretty bad... Also it's very hard to play it with the current camera, cuz I can't see much...
And why don't you add levels instead of an infinite level?
Overall not the worst I've ever seen...
Keep it up, you'll improve

Very cool game!
The story is cool, the gameplay is responsive and good, the dialogue, animations, I loved it!
Keep it up!