That's all fine and good, but you still haven't convinced me that the Church hasn't always had the same teaching on the Eucharist. From the Apostles right on down until today.
The term “Eucharist” originates from the Greek word eucharistia, meaning thanksgiving. Those believing in Christ (who is God) have always been thankful for Him ... not just the apostles. We give thanks to Jesus for all He has done and is doing ... that does not have to be done through religious ceremonies. Being thankful is a condition of ones heart towards God.
“O Come, let us sing for joy to the Lord; Let us shout joyfully to the rock of our salvation. Let us come into his presence with thanksgiving; let us make a joyful noise to him with songs of praise! For the Lord is a great God, and a great King above all gods.” Ps. 95:1-3
"I will give thanks to you, LORD, with all my heart; I will tell of all your wonderful deeds.” Ps. 9:1
"I will give to the Lord the thanks due to his righteousness, and I will sing praise to the name of the Lord, the Most High." Ps. 7:17
"Let your roots grow down into him, and let your lives be built on him. Then your faith will grow strong in the truth you were taught, and you will overflow with thankfulness." Col. 2:7
"And let the peace of Christ rule in your hearts, to which indeed you were called in one body; and be thankful." Col. 3:15
"Devote yourselves to prayer, being watchful and thankful.” Col. 4:2
"Every good gift and every perfect gift is from above, coming down from the Father of lights with whom there is no variation or shadow due to change.” James 1:17
"Give thanks in all circumstances; for this is the will of God in Christ Jesus for you." 1 Thess. 5:18
"Oh give thanks to the Lord, for he is good, for his steadfast love endures forever!” Ps. 107:1
"Giving thanks always and for everything to God the Father in the name of our Lord Jesus Christ,” Eph. 5:20
"The Lord is my strength and my shield; My heart trusts in Him, and I am helped; Therefore my heart exults, And with my song I shall thank Him." Ps. 28:7
"I will praise the name of God with song, and shall magnify Him with thanksgiving." Ps. 69:30
"Give thanks to the Lord, for he is good, for his steadfast love endures forever. Give thanks to the God of gods, for his steadfast love endures forever. Give thanks to the Lord of lords, for his steadfast love endures forever; to him who alone does great wonders, for his steadfast love endures forever; to him who by understanding made the heavens, for his steadfast love endures forever; ..." Ps. 136:1-5
Many many more verses about being thankful. Yes throughout the Word of God (OT and NT) it is taught to be thankful. We don't have to participate in a religious ceremony to be thankful and neither did the apostles.