How do I structure a paper so it can actually get published?

You can write. Sentences come. The trouble is the shape of the whole thing, and that is a separate craft. A publishable paper is not good writing poured onto a page. It is an argument built in a set order that readers and reviewers expect. Most strong papers follow a quiet skeleton. Here is the question. Here is why it matters. Here is what others missed. Here is what I did. Here is what I found. Here is what it means. When your draft feels like a pile, it usually means one of those pieces is missing or buried. Take your current draft and write one sentence for each of those six parts, nothing more. If you cannot write one cleanly, that is the part to fix first. Build the skeleton before you worry about the prose.