This solid groundwork for a larger project.
The artistic style is polished, and the obstacles just varied enough to be sustainable.
That being said, the player needs more to keep them playing over again than a score attack feature. As others have stated, upgrades would go a long way to these ends. Especially considering that as it stands, gold has no other purpose than to be a scoring mechanism-- made redundant by the actual score. That gold has no use is doubly an issue; the player has no obvious incentive to collect it otherwise, aside from the aforementioned score, thus further emphasizing the redundancy.
You're getting there. Best of luck in your next attempt.