Even it if only grabs you once, you can do the jump. I found out that you don't even have to jump from the skyscraper, you can do it right from the bottom with a double jump and the hand grabbing you once. go to the nearest edge on the island, run a bit onto the water (though the hand shouldn't grab you) then do the double jump, where you wait as long as possible with the 2nd jump. finally the hand will grab you. you don't have to reach the island, it's enough if you get almost onto it then a cutscene is activated, so just don't give up.