1 Corinthians 15:45-49 45 So it is written: “The first man Adam became a living being”[f]; the last Adam, a life-giving spirit. 46 The spiritual did not come first, but the natural, and after that the spiritual. 47 The first man was of the dust of the earth; the second man is of heaven. 48 As was the earthly man, so are those who are of the earth; and as is the heavenly man, so also are those who are of heaven. 49 And just as we have borne the image of the earthly man, so shall we[g] bear the image of the heavenly man.
So, does this passage say that Adam was the first man ever? No, otherwise it would be also saying that Christ was the last man ever. Adam is the first in a series of two, and Christ is the second in that series of two.