Who is Raymond Reddington in the Blacklist?

Ok so I started watching Blacklist on Netflix a month ago and completed all seasons, and since the show never fully and directly revealed who James Spader really is, I think its time to ask "What is the real identity of the person we know as Raymond Reddington portrayed by James Spader?" Is he the real Raymond Reddington, is he actually Katarina Rostova, or someone else?

Note: There are a couple of questions similar to this question already, but please note that they are asking a different question about relationship between Red and Liz. This question is about Red's identity only.

Raymond Reddington is Katarina Rostova.

When Liz is being told the whole truth in season 8, in the discussion between Ilya and Katarina, it is clearly portrayed that the real Raymond died due to the gunshot from little Liz. When Ilya and Katarina are discussing their next move in the hotel room, they decide to steal Raymond's identity in order to get that stashed money, with Ilya using fake beard to identify as Red. However, once they have the money, they use it to give Katarina a new identity, that of Red which is indirectly implied from their discussion.

2 Seasons before when Liz faked her death, we have a full episode where Red dreams of trying to drown and then fight the KGB agents in the form of Katarina, in season 8 this is revealed that the real Katarina actually did go through this. So Red could only dream of this if he was Katarina.

We also know that Katarina's father Dom back then hated America and Raymond Reddington to his guts, but if he is now in America and in company of Red then it could only be because he knows its his daughter and not the real Raymond.

Plus Red never lies to Liz and he never ever says that he is not her parent, he just says he is not her father, which is correct because he is actually her mother. He also tells her multiple times that Liz shot her father and that he is dead.

Since Katrina became Raymond from sex change operation and plastic surgery to change appearance, internally she is still female. Many times throughout the seasons Red does stuff that females would be more comfortable doing, and since he does not have manly strength he is never shown fighting muscular men, Red just shoots them because despite being KGB trained fighter he still has muscles like a woman and not a man.

The skeleton remains that Mr Kaplan gets delivered to Tom after dying are probably of the real Raymond's, but probably Mr Kaplan thinks they are of Katarina because maybe she does not know the real identity of Red, because if she knew Katarina was Red then she wouldn't go through all that trouble of saving Liz from Red. So when Red burns the skeleton, Dom is disinterested because he knows that they are not of Katarina, its just the real Raymond.

Also, Ilya so loyal to Red that he would rather kill himself than tell anything about him to the imposter Katarina, could only be arising from his true love to Katarina.