What you’re saying makes sense up to a certain point. Unfortunately, it’s easy to take this kind of logic too far. When that happens, as it frequently does nowadays, you end up throwing out the baby with the bathwater.
Nowadays people like to say that the only ultimate reality is personal opinion. This is especially true where “religion” is concerned. It’s “my beliefs” against “your beliefs,” and there isn’t anything solid or objective against which to measure our different viewpoints.
This may be true if we’re talking about some of the customized, mix-and-match “spiritualities” that have become so common in modern society. But it doesn’t apply to Bible study. Why not? Because when we turn to the Old and New Testaments we find that there is something else besides our own prejudices and preferences that has to be taken into account: the text itself. Among other things, it introduces another Mind (or minds) into the conversation. If we want to read the Bible seriously, we have to ask some thoughtful and discerning questions about the intentions of the people who wrote it.
Don’t misunderstand. We realize that people can take a book like the Bible and try to make it mean whatever they want it to mean. That doesn’t prove that they’re justified in doing so. The words of Scripture do mean something in their own right, whatever you or I may say about them. What’s more, they can be misrepresented or misconstrued. So it’s not just a matter of “personal interpretation.”