Nothing happens if human have wings but humans can do miracles with the help of wings humans can achive anything what he needs to some extent only
If a human were to have wings  we could achieve new heights and not only be able to think out of the box but go out of the box. we would reduce pollution by travelling places with our wings and not pollute the air with vehicles. fiction movies which include people flying can be done easily and wont be fiction any more. there are cons too. security like fences and so on can be over come easily as people would be able to fly over fences and stuff . it could sometimes be dangerous too when we fly everywhere . since we have already spoilt our earth and taken over it we will find a way to takeover the skies too and maybe pollute it even more thus destroying it .so it could be harmful in ways to have wing s but there are plenty of pros to it to .