There is nothing in Christian antiquity that suggests the early Christians believed Holy Communion (the Eucharistic body and blood) was merely symbolic. Indeed, the burden of proof falls on the Protestants when they say otherwise.
The wording in the Bible is clear. It is a remembrance until He comes again. It doesnt turn into anything. It doesnt bestow any extra grace.
Up until the time of Luther the only thing was “The Real Presence.”