This is a result of salvation, not a means of salvation.
Holy Thursday and Good Friday are one Sacrifice.
And this is the self-same sacrifice as the Sacrifice of the Mass --- same priest (Christ), same sacrificial offering same Body and Blood (Himself) --- not done "again," but made present as an eternal offering.
Holy Thursday AND Good Friday AND the Mass are one Sacrifice. This is eternal: this is the Lamb that was slain before the foundation of the world.
You have to stop and think of that a minute. "before the foundation of the world." That's why it has this aspect of being both "in time," and "timeless," beyond time. It is not repeated: it is extended into eternity.
Salvation itself --- what Heaven is --- is Communion with Christ and with all the saints (the Body of Christ) That is salvation: and the Sacrament of the Eucharist on earth is a foretaste of that Communion. It is a generous distribution of this (eternal) oneness --- He in us, we in Him --- right here on earth. It is an earthly partaking of the Heavenly Banquet.
It is for sure a remembrance, but far beyond what we could call a remembrance of earthly things, which is just nostalgia, or an imitation performance. THis is not cosplay. We are not re-enactors.
It is an actual participation in Christ's sacrifice now, on earth as it is in heaven. It is an actual participation in the past the (Upper Room, Calvary Hill) and the future (Heaven) at once, in this eternal now.
If it's to be called a symbol, then it is a symbol that conduces into reality, and a remembrance which does not just represent, but which RE - PRESENTS. It make us presently "present" with Christ, whose Real Presence is with us and in us.
In a way,it's not "preparation for Heaven" or "a way to get to Heaven", but it is Heaven itself, for it is Chris, and where He is, is Heaven.