If affecting yourself with and adjective, feminine form would be used, whether short form or long form.

When it comes to asking how you are, there's a bit more detail to pinpoint
я хорошая - I'm good (of a person, as in quality of character or something)

The answer to как is, roughly speaking, an adverb [like хорошо], whereas какой would ask for an adjective.

-Привет! Как дела?
-Хорошо! Как ты?
-Нормально.

or

-Привет! Как ты?
-Нормально, вчера выписался из больницы.

Think of it as asking "How are things (going)?", with the word going being omitted, so the answer is "(going) well!"
"хороши!" is not correct

https://www.youtube.com/watch?v=XXVTnCVnlJU

The extent to which this rule holds up is fairly questionable, but the functional idea behind short adjectives is:
Using a long adjective implies that there is a noun being modified by the adjective, and that there's a verb floating out there somewhere; whereas short adjective tell you that the verb for the sentence *is* itself in the presence of that short adjective. Frees up word order even more.

"Чтобы дикий этот смысл простичь и охватить, надо много жизней проволочить в лагерях — в тех самых, где и один срок нельзя дотянуть без льготы, ибо изобретены лагеря — на истребление." А И Солженицын - Гулаг Архипелаг

ибо изобретены лагеря — на истребление.
, for the camps were developed - for extermination.

If the adjective had been long, it would have come out:
, for the developed camps were for extermination.

https://www.youtube.com/watch?v=g7zMEL_ig4Y

"Я, как призрак, удивительно хорош."