Hello. If you mean the jump where you have to jump across the gap, you can use shift button to increase your speed. Maybe this will help. Let me know if it does and you reach the end :)
A few more things. Are the graphics fixable? It kinda messes with me. Could you make it so you can hold shift and jump at the same time? that complicates the game a bit. lastly, is there a reason for the key in level 1? Also, could I get your email address? It would make this a lot easier, and probably better for you too so potential errors aren't publicly pointed out.