I opened your file, then saved it as html – the result, as hoped for, included a subfolder with graphics, but (even with the Filtered option) the code is so densely laden with Wordery this didn't get me very far. Next option, ruthlessly: save as plain text: graphics gone, and clean content ready for formatting and spell-checking. You could then reinsert the graphics that Word saved out into the subfolder, though the quality is not ideal:-} artefacts (speckles) as though line drawings had at some stage been saved as .jpg.

The adage used to be, "trying to get a source document out of a .pdf is like trying to get a chicken out of chicken soup". <g>