Who are the 144,000?

Oh dear I realize Revelation is in symbolic language.  I realize all of them who sing a new song before God's throne are not from Israel's tribes.  But by saying they are the writer gives us a clue about who they really are. I do not presume to know who they are.  I do not assume I am correct the names on there foreheads are NOT Jesus and Jehovah.  But seeing that we don't know I think it is wrong to assume they are especially since one Name has been declared Holy times three.  The law of Moses says that if a clean thing is touched by an unclean thing the clean thing becomes unclean and not the other way around.  

It is written in the Watchtower that living people are of that 144,000.  If a living person is one of the 144,000 when does it get The Name?  It can't be on his forehead NOW.  But what is on their foreheads is what identifies a person that way. Logically can anyone see that living souls who have not endured to their end cannot be having God's Name on their foreheads?  So if on their foreheads is Jesus and Jehovah there aren't any of the 144,000 on earth ever.