It occurs to me that the "you're helping" might read as snark and it wasn't really intended that way, or at least, not as snark at you, but rather all of us.
It's silly to reject help from e.g. peer review, static analysis, smarter / safer languages. If you look at some tool and say "What kind of idiot would make the mistakes this catches?" the answer is almost certainly "idiots like you".
isSorted([0, 0, 0], [4, 20, 0, 0, 0]) is true
(the code doesn't care about values in sorted which never occur in original and doesn't check these arrays are the same length)
But
isSorted([10, 5, 0], [0, 5, 10]) is false
(for some reason the code checks that original is sorted, rather than sorted...)
That's OK though, the original exercise exists because most programmers can't get even basic algorithms right, so you're helping to demonstrate that.