Until you started this thread, I don't think I was aware that there was a Humble Daily deal, so well done, I guess. Is it new?
When I went to the Humble Store looking for the Daily I was able to find it, but I'm not sure I'd notice it if it weren't pointed out prior. The skinny little corner banner doesn't do much to call attention to the one of many in a full page of images.
Also, it seems to be 3rd in the queue of the feature carousel at the top of the page. I would think you'd want it to be first.
Finally, there was no mention of the daily in the Humble newsletter I got today. I assumed it was XCOM 2.
There's your unsolicited feedback for the day. Good luck with the dailies!