The purple chest key is in the down-leftmost silver chest and the door key of that chest compartment is before the spears on the right side which I intensionally made unnoticeable. And for the jumping problem if you press R you'll directly spawn on your last checkpoint which will not cost any life currently. The only mistake I made was that I put an extra checkpoint before the purple chest compartment which caused the problem not being able to go back and get the key and also the mistake of triggering camera animation without opening the purple chest. I'd be sure to fix those problem. Thank you!