Word for -> “This is amazing!” + “I’m a moron. How did I not see this before?”

Solution 1:

I can think of no single word that means exactly that, but a now popularized expression is d'oh.

[Merriam-Webster]
—used to express sudden recognition of a foolish blunder or an ironic turn of events

Although it's somewhat lacking in the "this is amazing" sense, it's more than sufficient in the "I'm a moron" sense.

Generally speaking, it can be used after doing something stupid without the intended result, and then watching something else do something much more intelligent and producing exactly what was intended.

It can also be used to express your own stupidity for not noticing something right in front of your eyes. For instance, spending 5 minutes hunting for your glasses only to discover that you've actually been wearing them all along. You're happy to discover where they are, but annoyed with yourself at the same time.