I always thought the whole "You don't play as Big Boss" thing was so silly... but it may be happening. So surreal.
There are still a lot of questions.
Who is Ishmael?
Who is Ahab?
Who is the Medic?
Is anyone Gray Fox?
If we are Fake Big Boss, what was the real Big Boss doing?
What is the fate of our player character?
What is Ocelot doing? The spoilers never mention him, yet I can't believe Ocelot is in a MGS game without pulling some shenanigans.
What's the significance of Psycho Mantis being a Big Boss clone? He was a memorable character in MGS1, but didn't have a whole lot of significance in terms of the meta story.
If Mantis is the third Big Boss clone, what's up with Solidus?
Why the eff is Volgin back? How is he on fire?
These spoilers just give me more questions than answers.
Ahab and Medic seem to be the same person, if you are Ahab then you're Medic, he protected Big Boss at the end of GZ, BB seems to have no shrapnel in his head in the hospital cutscene
Venom/ahab/medic is probably either Decoy Octopus or a body double, either way, nanomachine hypnotism is what makes the doppelganger think they're the real Big Boss.
Ishmael was also voiced by Keifer, so he's either the real Big Boss, or he's Solidus, Solidus was born
after Eli and David (and to a different woman, his mother is not Eva) but he aged much faster in general so he could potentially nearly be an adult by the time Eli is a young teenager, who knows if that's how it worked.
The real Big Boss is probably trolling everyone from a cardboard box somewhere.
I don't believe Mantis being the third child is referring to the sons of Big Boss, Eva just had twins, she said so herself, and Solidus is the 3rd "son", so if they were trying to say Mantis is a clone/child of Big Boss, he would be the 4th child.
We also know from MGS1 that he grew up in a small village, he had a father that he killed, but when he opens the secret passageway for Solid Snake, he does comment that he never used his powers to help anyone before now, but that it still felt nostalgic.
How is Volgin back? Illusions, psychic projection, corpse manipulation, take your pick, Mantis can do all that with no real trouble, illusion fire was a thing he did in MGS1, so it was kind of easy to assume he was just making you see stuff that wasn't really there.