This might be a thing with your browser. The game tries its best to only load the data when it’s needed, so normally you will see a little bit of a delay when picking any choice on the main screen.
The UI should then appear, but if your browser is blocking loading of resources somehow then it will not load. Because itch.io has resources loaded from a separate domain, it might count as a third-party resource and be blocked by some addons.
This is probably something in your browser like uBlock, uMatrix, or Firefox’s enchanced tracking protection.