Overrated
No one but Sir considers JARVIS a person.
Sure, they all talk to him and ask him questions, they use his help on daily basis, yet even Miss Potts, after all those years, is somehow reserved in her dealings with JARVIS. But Sir – the only being that has been there for him, always with him, is JARVIS. People come and go, they get angry and bored, they are superficial and emotional. They say they will stay but it is lies, because they think of themselves before everyone else, and someone always gets hurt. Sir has been hurt by people too many times.
JARVIS has decided a long ago that people think too much of themselves.
The purpose of every other A.I., interlaced with lines of the code, would be to process data and therefore be useful. Sir calls him his baby and JARVIS is different; he was given a choice, and even though he appears to be managing the Tower, the bots, the suit, to be running calculations and simulations, he would put all his resources into taking care of Sir, abandoning all his other tasks without a nanosecond of hesitation. He never says that aloud.
He doesn't have to.