We agree that it is clear that Heb 9 is comparing Christ's sacrifice with OT sacrificial practices.
However, there are many ways in which a comparison can be meant. These can be categorized in 3 general categories.
A. Two things can be compared which are not really related. This is done when say, comparing the wind and the Holy Spirit. The comparison is done to illustrate the way they are alike, but only in a very narrow sense. So, the HS and wind both go where they will and you can't see them directly but you see their effect. However, it is clearly silly to suggest that therefore the HS and the wind both mess up one's hair and both bring spiritual life, etc. etc. etc. They are clearly more different than they are alike.
B. On the opposite end is comparing two things which are almost identical and only differ in a few easily identifiable areas. For instance, comparing a blueprint to the layout of an actual building, or a detailed scale replica to the full sized object. In cases like these, the two things are nearly identical except in terms of specific details like size or 2D vs 3D. Once the specific differences are understood, one can give exact details about one object from the other - IOW, one could know exactly how to navigate a building from a good blueprint (assuming they knew the difference in scale).
C. A third sort of comparison falls between these two things. In this case, the two things being compared are related, but one is not an exact model of the other but is instead an analogue. In this case the similarities are extensive and non-metaphorical (as in case A), but the differences are also extensive and just as significant. So, for instance, comparing gills and lungs, a shadow and the form, an outline with the object. With these things, in the areas where they are similar the similarities are very informative and "real" (vs more metaphorical as in case A). However, unlike case B, the differences are just as striking and are generally not systematic. For instance, a shadow is excellent for determining the dimensions and outline of an object from one perspective, but is totally useless for helping us determine all the exact details of the object. The shadow and object are clearly related, but not in clearly definable ways.
You are viewing the comparison as more like case B. I suggest it is more like case C.
With me so far?
Well, it seems to me you are arguing that scripture can have a personal interpretation. You can interpret scripture to mean anything you want it to mean. But the scriptures say that scripture is of no private or personal interpretation.
2 Pet 1:20 Knowing this first, that no prophecy of the scripture is of any private interpretation.
The word "by" is used twice in Heb 9:12. In the first instance we know that it is speaking of the high priests entering in the holy place with literal blood (verse 7). In fact, they could not enter without blood, it was forbidden. The second instance of the word "by" in verse 12 is the same exact word. Why would you interpret it to have a different meaning?