It's not an interpretation of what he said. It's unambiguous. Period.
But you dodged my question: Was John the Baptist the son of Elizabeth and Zechariah?
No, I didn't dodge the question. I said however it was accomplished, christ has answered it. Elizabeht and Zechariah could well have given birth to a new body for Elias - or they may have found and adopted him. Who knows and who cares. His physical body could not enter heaven, we know this from Paul. So one can play any number of games with this, it changes nothing Christ said - and without any ambiguity, he stated that John and Elias are one in the same.
No, they couldn't have just found or adopted him, otherwise Luke is lying when he says the Holy Spirit tells Mary that Elizabeth is in her sixth month of pregnancy. Thus, we're left with your option of Elizabeth giving "birth to a new body for Elias."
There's a word for that, Havoc. It's called reincarnation. And historical Christianity has always viewed this as a doctrine of demons.
But I'll play along. Given John the Baptist's body was a 'new body' for Elijah's spirit -which is your argument- what happened to his old body. Is it still hanging around up in heaven, spiritless?
Earlier, I pinged some Protestants to this discussion, wishing to get their input. Unfortunately, none have yet commented. Perhaps they would wish to do so now.