What we celebrate in the Church today as Holy Communion is based on a real event - the Last Supper - but it is unlikely that it took the form which we use today.
In the ancient world the meal was a symbol of communion with the god.
It was the culmination if the initiation rites in the mystery cults.
The cult of Dionysus for example used the meal as a reminder of the death of Dionysus and his being eaten by the giants.
Some think that this myth is the basis of the Eucharist.
Dionysus' heart was taken to Olympus and he was given a new body.
That being said, the event which we call the Last Supper was a Passover meal.
And as such it was a celebration of the covenant between God and the people of Israel in Egypt.
The blood of the sacrificial lamb was painted on the door of each Israelite's house and the plague of death passed over them, sparing the lives of their firstborn.
It was the commemoration of this meal which Jesus and the disciples engaged in that night.
As a reminder of the covenant between God and Israel, Jesus may have used this meal as a symbol of the new covenant centered in him.
It is unlikely that he would have used the words my body and my blood.
This is much moire likely to be an overlay which was added later, after his crucifixion.
But this Passover meal remains a covenant with God and we are right to commemorate it as Holy Communion.