I remember my first Deer, it was more luck than skill. I had Buck fever pretty bad, the Adrenalin was pumping. All I could really see was a Deer, my sight picture was all wrong, the Deer was in sharp focus and my front sight was fuzzy.
Make sure your marksmanship is good, practice. Aim small, miss small. I pass on a lot of shots, I'm a selective shooter. I've tracked too many of the other guys mistakes and learned from my own mistakes and theirs.
Sounds like you put in a reasonable effort, in fact beyond reasonable. I'd chalk it up to bad luck more than lack of effort. After 4-5 hours I usually take a break and call in some help. It is always nice to know someone with a dog.
No matter how good you are. there is always the chance of a twig between you and your target and a less than perfect shot. Or the Deer bolts right as you shoot or a dozen other things that can go wrong.
Nice that you shared your mistakes, it may keep someone else from making the same mistakes.
I feel a large sense of satisfaction when my Deer goes down in a pile, DRT. It is the high point of my hunt.
I had a Hog do the same thing your Deer did, laid there looking dead until my dog stuck his nose up that Hogs butt.