I think part of the problem was the canvas is being rendered below native resolution on a retinal display, so the blurry upscaling made it look like a screenshot.
None of the spreadsheet apps I tested have hover styling, but that seems like a violation of basic UX principles. Cells are the primary element of interaction, so I would expect some visual indicator to communicate interactivity (even if it is just the cursor changing).
This certainly feels interactive when I interact with it like I would any other spreadsheet. Are you unable to select cells and/or type in them?