But why theologically speaking is it important that its literal blood and flesh? What is the significance of it salvation-wise?
Traditional Christian theology would assert that our salvation is the work of God to rescue us, redeem us, etc; and He does this by bringing us into and uniting us with Christ--Christ who died, Christ who is risen, and Christ who is coming again. Thus salvation is not merely some contractual decree, it is about taking a world of sinners, bringing it into the Person and work of Jesus, and in Him it being healed, renewed, and restored--ultimately and fully on the Last Day at His return in glory, at the resurrection of all the dead, and the everlasting life of the future good world "A new heavens and a new earth", what we call the Age to Come.
A mere memorial meal may have a subjective meaning or a sentimentality; but the Eucharist is more than sentimentality, it is a living encounter and participation in the death, resurrection, and life of the Crucified, Risen, and Glorified Christ in Who alone is found our salvation--our salvation which He caused at Calvary by His dying for our sin, our salvation which He caused by His rising from the dead and defeating death, our salvation which is ours now through faith, in the promise and life of God in Christ by the Spirit, and our salvation on the future Day when Christ returns, the dead are raised, and all things are made new.
This isn't mere bread and wine done for the sake of sentimentality, or as a nice pious ritual; it is Jesus Christ Himself, living and incarnate, the Crucified and the Risen, our Lord, our God, with us, present for us, in our amidst, nourishing us with faith, administering grace upon grace that we, indeed and truly, have life in Him. Not out of our own efforts of obedience which fail and for which none of us could stand before God; but by the grace of God alone, in Christ alone, it is His work alone.
-CryptoLutheran