The game is kind of enforcing the speedrunning flow, and it can be a bit frustrating for people to restart from the very beginning. Games like Geometry Dash solve this by providing a practice mode - so you would play the game with checkpoints first, then start making actual runs (it's actually how speedrunners do it as well lol!)
Additionally, player's interaction with environment should be a bit better - sometimes enemy hitboxes or appearing lasers felt unfair. But the movement felt nice, no complains in this regard. I actually went ahead and gave a couple of more attempts after completing the game, managed to finish it in 58 seconds!