Present how? Spiritually present? Jesus is always and everywhere spiritually present. What makes the Eucharist different is that Jesus is completely present in His Body, Blood, Soul and Divinity.
Jesus is not just Spirit, He is also a physical flesh and blood man. But in His flesh and blood humanity His Soul and Divinity resides.
It is by receiving His flesh and blood, that we receive life to our flesh and blood.
Jesus didn’t take Simon in His hands and say ‘This is Kepha ( Rock ) ‘ He changed Simons name to Kepha Rock. When God granted authority to someone, He changed their name, as with Abraham.
When Jesus said ‘ that Jesus is water, that Jesus is a key stone, that men are literal sheep, and that Jesus is the vine ‘ and the gate. People knew he was talking metaphorically, none took it as literal, and Jesus didn’t have to correct them as He always did when they misunderstood.
Jesus didn’t correct the disciples that walked away, because Jesus was speaking literally and meant it literally, that His flesh was real food and blood real drink.
Jesus doubles down, triples down and quadruples down speaking this “ hard “ and very literal “teaching “.
The disciples that deserted Him did so because they rightly understood Jesus was speaking literally, but they could not believe.
Jesus is The Truth, The Whole Truth and nothing but The Truth, He would not allow disciples to walk away with a wrongful understanding, they walked away because they rightly understood Him, but could not believe.
“This is why I told you that no one can come to me unless it is granted him by the Father.”
The words Jesus spoke were spirit and life, meant to be believed by spiritual Faith granted by The Father, not understood of the flesh, human reasoning.
“ Will you also go away ?”
It’s an impossible teaching to believe, unless by spiritual Faith in Jesus words.
Peter makes that supernatural act of Faith in Jesus words and believed Him.
Peter and the disciples did not fully understand, but they believed it because Jesus said it. “ You have the words of everlasting life “.
There was one marked disciple that remained, but did not believe Jesus words.
64However, there are some of you who do not believe.” (For Jesus had known from the beginning which of them did not believe and who would betray Him.)
“Have I not chosen you, the Twelve? Yet one of you is a devil!”
71He was speaking about Judas, the son of Simon Iscariot. For although Judas was one of the Twelve, he was later to betray Jesus.”
Judas did not believe Jesus flesh was real food and blood real drink, but ate anyway at the Last Supper.
“ When Judas had eaten the bread, Satan entered into him. “
Thankfully it isn’t a valid Eucharist among those denominations that do not believe Jesus words literally. It does not end well for those that receive the Body and Blood of Jesus unworthily or without belief.