Your supporting statement is filled with speculation and/or extrapolation.
Jesus was standing right in front of them when He instituted this Remembrance, and He had not yet been to the cross. The bread and wine couldn't possibly be His body at that time (or ever). It makes more sense, and is more in line with His parable method of teaching, to view this as metaphorical symbolism.
Symbolism detracts nothing from the importance of this Commemoration. It is certainly required that we pay proper honor and respect to the Sacrifice which we remember. Thus, Paul's warning remains valid and pointed.
I'm not sure what you mean by, It is therefore not a matter of agreeing to disagree as in some other aspects of the scripture open to interpretation. Clearly we disagree. If we cannot agree, we have no choice but to continue in disagreement, and thereby agree to do so.
This only means that every Mass is a connection across time to the same sacrifice of the Golgotha. Likewise, you would note that the Precious Body is present in many churches and many ears following the Cross.
The Scripture does not leave a clear teaching whether the Last Supper had Real Presence in the elements as well as in Christ in the natural sense, but that surely does not point to the symbolic or mere memorial future act, since the commandment is to "do it" at times future, relative to the Last Supper.
If we cannot agree, we have no choice but to continue in disagreement
True. What I mean is that there are things that the Church teaches, yet other reasonable explanations of the same scripture exist. For example, one can make a reasonable argument from scripture alone that Baptism cannot be given to children, or that divorced people may remarry if the divorce was on grounds of adultery (the Church teaches that children before the age of reason may be baptised, and the marriage after any divorce may not happen). This is not one of such cases: the totality of the scripture alone, and especially 1 Cor 11:29 exclude the Protestant view of symbolic presence.