"njema" is for N-class-nouns (9/10); people are in classes 1/2
"Rehema ni mwema." which would mean that she is good(hearted) - ~ema refers to the character of something/someone rather than state or health...
Here's what I picked up:
Mimi sijambo (I)
Wewe hujambo (you sg)
Yeye hajambo (he/she)
Sisi hatujambo (we)
Nyinyi hamjambo (you pl)
Wao hawajambo (they)
Not sure though, confirmation or correction would be welcome.
The prefix ha- usually indicates a negation in the 3. person singular
(same for si- in the first person singular).
However together with Jambo it appears to be different
--> Hajambo / Sijambo give positive answers.
Why is that?