Why are you more focused on Paul, rather than on the Gospel, which proclaims the Truth?
The beloved disciple, John, the last of the New Testament writers, wrote his Gospel in the 90's. John was an eyewitness to the events of the Last Supper (Jn 6:30-68).
Hence Catholic Christian belief in the real presence of Jesus Christ in the eucharist rests upon the literal meaning of the words of the Last Supper as recorded by the Evangelists and Paul.
The uniformity of expression across the four authors affirms the literalness. Belief in the real presence demands faith--the basis of new life as called for by Christ throughout scripture. But faith in signs conferring what they signify is the basis also for the Incarnation--appearances belying true meaning. The true significance of the real presence is sealed in John's gospel. Five times in different expressions, Jesus confirmed the reality of what he means.
The best way a person can make a clear literal point is repetition of the same message in different ways. Jesus did this. Those around him clearly understood what he was saying--cannibalism and the drinking of blood--both forbidden by Mosaic Law.
Had these disciples mistaken the meaning of Jesus' words, Jesus would surely have known and corrected them. He didn't. They had clearly understood his meaning--Jesus' flesh was to be really eaten; his blood to be really drunk.
Do you realize that by your statement, you are implying that Paul is lying and deceiving and presenting a false gospel? It isn't a matter of one is Truth and the other isn't. They both are.