If you worship a thing, it is your idol - your god. There is a difference between having a representation or image as a focus to remind you of a who or what and having that same thing as the object of worship in and of itself.
The Hebrew people in the desert, while Moses was being given the Ten Commandments, come to mind. They grew impatient and made a golden calf. They did not say the golden calf was a representation of a god, but rather that this thing they themselves had made was a god.
When we make a statue of a saint, we don’t believe that statue is the saint, but rather it is an object of art to inspire us, to remind us of the saint and serves as a focus when we ask that saint for their assistance (intercession).
Similarly, when we make the likeness of Jesus on the crucifix (or anywhere else), we don’t believe that thing is actually Jesus, but only an object of art to remind us who and what Jesus is. We don’t worship the crucifix, we worship what is reminds us of - the second person of the trinity as one in essence and being with the Godhead.
The monstrance is a thing. You could think of it as a throne to allow the Blessed Sacrament to be made easier to view by the faithful. It is not a container for “sacramental bread” but rather a throne for the body, blood, soul, and divinity of Jesus Christ, made present through the miracle of the consecration during the Mass. When we pray in front of the Blessed Sacrament in the monstrance, we are not praying to or in front of “sacred bread” but rather we are praying to Jesus who is present, right there in front of us in the monstrance, in Bethlehem. (Beth-lehem is Hebrew for “house of bread”)