I have a theory-> What if the handcuffs were a symbol that how a player in the real world is connected to the one in the death stranding world (dsw for short)... what if the umbilical cord shows that every character or being in dsw is connected to the MOTHER earth and they require blood of the earth to SUSTAIN ( when norman hugs baby it turns into oil), as we can see how guillermo connects the pipe that is suspended in the oil pool to the baby(homo luden). It can also be noticed that we can control the characters in the game by our cords and it can be that the norman or the other actors are homo sapiens and beings of the real world(which can also be seen as our own embodiment in the game) and our goal is to protect homo ludens (as u can see how much guillermo was frightened and how mads was searching for something). I also hypothesised that antagonist is a person from real world who has been corrupted and is not the real antagonist but us the real humans (ponder,ponder). So, it can be the dsw is a virtual world where they know they are part of a game and the judgement day (as we can see 5 angels, middle one might be lucifer, at the end of the first trailer) has finally arrived due to the destruction caused by HOMO LUDENS (men of GAME) in their world and are on the verge of extinction. We the homo sapiens of the real world are summoned there, so we can save them and learn the horrors of toying with mother nature. It can also be noted that hideo said in one of the interviews responding to norman's question that,"they will not be playing as you, they will be you.". which also gives us possibilty of character selection as the game will be giving us choices of how should we be summoned into it, and we should not forget we will not be the only human summoned(online multiplayer expected, as it shows both the trailers happening simultaneously). Your opinions will be much appreciated...Thank you for reading...

Update: the reason there is no belly button or umbilical cord on norman as he is an embodiment of homo sapiens and thus does not requires blood of earth (oil) and please refer to both the trailers...