In the Spirit and power of Elijah. In other words "from God" is the importance not the person. Do you think then Jesus, (The head of the body of Christ), answered the question wrong or was mistaken?
No, he wasn't wrong or mistaken. It is, however, a spiritual statement. If it were literally Elijah, his name would not have been John. That rather goes without saying. However you fail to address the elephant in the room.
Hebrews 9:27 And as it is appointed unto men once to die, but after this the judgment:
1 Corinthians 15:22 For as in Adam all die, even so in Christ shall all be made alive.
These are just two verses out of several that state all men will die. It is our flesh nature that must be put off in order to put on immortality.
Enoch and Elijah have never died this death.
While God can do anything, he will not lie. His word is true. Therefore, that's who they are. Otherwise his Word states that there are two men who have never died and will live forever. Seeing as how Jesus will come a second time, there needs to be "an Elijah" there as well as per Scriptures. John was in the Spirit and power of Elijah, so "spiritually" it is Elijah, but it isn't really him. We are not reincarnated into other people. So you've largely missed the point of Jesus saying in Matthew 11:14 And if ye will receive
it, this is Elias, which was for to come. However John himself in John 1:21 And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No. So while both statements seemingly conflict, spiritually they do not. The only way for them both to be correct is for them to both be correct. That is also why Jesus states afterwards in Matthew 11:15 He that hath ears to hear, let him hear. (understand) Likewise, the Jews of the day did not understand either because they did not spiritually "get it".
It is also worthy to note, that in the days of Enoch it had not rained. Upon his son, Methuselah, it was imparted that upon Methuselah's death, the rain and Flood would come. Hence the name Methuselah means his death brings judgment. Elijah also stopped the rain (1 kings). So they already have the power and spirit which God gave them.
Concerning signs, Like the parable of the ten virgins, it best to be prepared for the groom, rather than wait until he comes then get the oil. Did not Jonah preach to Ninevah of the impending judgment upon their city? Can you not as Jesus said, read the signs of the times? Think what you will, interpretation is not a private matter. While the longevity of his plush lodging in the fish is metaphorically identified with Christ and his resurrection, it is not the sign of the second coming. it is a metaphor FOR his death and resurrection. Just repent....