For 13 to be unlucky would require there to be some kind of cosmic intelligence that counts things that humans count and that also makes certain things happen on certain dates or in certain places according to whether the number 13 'is involved' or not (whatever 'is involved' might mean).
Our actions seem to have their lucky and unlucky stars to which a great part of that blame and that commendation is due which is given to the actions themselves.
Only bad golfers are lucky. They're the ones bouncing balls off trees curbs turtles and cars. Good golfers have bad luck. When you hit the ball straight a funny bounce is bound to be unlucky.
Of moral purpose I see no trace in Nature. That is an article of exclusively human manufacture and very much to our credit.