They are both correct in a particular circumstance. The first one would probably be used when you want to say 'There is nobody coming anymore. (We can close the door.)' The second can be used to describe a past situation where no one came to your house or party. You can also use the second sentence to describe the present situation meaning there is no one here at the moment, but usually we would add "还" in front of the sentence - "还没有人来” means not a person here yet but probably someone will come later.

you can say 没有人 directly

没有人来。 no one came.

Suppose to be 没有人来。 This is because "了" like "-ed" in verb. If nobody is coming, then it will not be a past tense.

Suppose we have a party. In the first case, everyone is here, and then your friend asks you, is there anyone else? You can say that no one is coming. （没有人来了）In the second case, everyone has something to do, and they can't come. Then your friend asked you, how many have you been here? You can say that no one is coming.（没有人来）