That is absolutely NOT what Catholics understand to be true.
Since the bread and the wine to not change in physical substance into literal flesh and literal blood, there can be no other option.
Do you believed that God is some how restricted to the confines of what you are able to perceive? No doubt there were a great many people in Jerusalem a couple thousand years ago saying, "Jesus of Nazareth can't possibly be God, He looks just like everyone else."
It fallacious to believe that a change must be immediately visible to the naked eye to be real.
I've posted this several times before, but I will post it again because it is important. Ignatius of Antioch was an Apostolic Father, a student of Saint John, probably Saint Peter and possibly the child in Matthew 18:2. As a prisoner awaiting martyrdom he wrote several epistles; though the validity of some of these epistles is very questionable, the one I am quoting from has NEVER been disputed. You should note that the FIRST attribute he cites of heretics is their denial of the Real Presence and he wrote this no later than 108 AD.
The Epistle of Ignatius to the Smyrnæans
Chapter VII — Let us stand aloof from such hereticsThey abstain from the Eucharist and from prayer, because they confess not the Eucharist to be the flesh of our Saviour Jesus Christ, which suffered for our sins, and which the Father, of His goodness, raised up again. Those, therefore, who speak against this gift of God, incur death in the midst of their disputes. But it were better for them to treat it with respect, that they also might rise again. It is fitting, therefore, that ye should keep aloof from such persons, and not to speak of them either in private or in public, but to give heed to the prophets, and above all, to the Gospel, in which the passion [of Christ] has been revealed to us, and the resurrection has been fully proved. But avoid all divisions, as the beginning of evils.
They are ashamed of the cross; they mock at the passion; they make a jest of the resurrection. They are the offspring of that spirit who is the author of all evil, who led Adam by means of his wife, to transgress the commandment, who slew Abel by the hands of Cain, who fought against Job, who was the accuser of Joshua the son of Josedech, who sought to “sift the faith” of the apostles, who stirred up the multitude of the Jews against the Lord, who also now “worketh in the children of disobedience; from whom the Lord Jesus Christ will deliver us, who prayed that the faith of the apostles might not fail, not because He was not able of Himself to preserve it, but because He rejoiced in the pre-eminence of the Father. It is fitting, therefore, that ye should keep aloof from such persons, and neither in private nor in public to talk with them; but to give heed to the law, and the prophets, and to those who have preached to you the word of salvation. But flee from all abominable heresies, and those that cause schisms, as the beginning of evils.
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Not only do I sincerely hope this is not the case, I would be astounded if I were to be able to fully understand God. Imho, much harm has been done because of the arrogance of man.
The 15 forged letters of Ignatius:
"... Of later collections of Ignatian letters which have been preserved, the oldest is known as the "long recension". This collection, the author of which is unknown, dates from the latter part of the fourth century. It contains the seven genuine and six spurious letters, but even the genuine epistles were greatly interpolated to lend weight to the personal views of its author. For this reason they are incapable of bearing witness to the original form. The spurious letters in this recension are those that purport to be from Ignatius."