NFJ, probably INFJ because he seems introverted and more of a perceiving dominant.
I think he is 3w4 too, not a 4. He is a chameleon, a performer. He didn't seem like he wanted to be known outside of an image. With INFJs, when image types, it seems like their image is more of the drive behind the art than the art itself. 4s can certainly can cop an image and create a character (or many) but there is always something personal about them. Their personal meaning is communicated via an image or artwork. It's a means, not the end. Bowie didn't seem concerned with being personal, IMO. I am absolutely vibe typing now. In interviews, he vibes a bit like Daniel Day Lewis (INFJ 4) to me.
That's (the bolded) what I was trying to get at, you just said it more coherently than I could.
While it can be dangerous to type an artist based on their work, I think it's helpful in Bowie's case, since he was a very private man and didn't reveal a lot to the public world (except what he wanted to reveal; he could be very tactful and clever in how he could play interviewers, especially in his later years).
Take Lennon's lyrics. He seemed to value bearing his soul and values in his lyrics. He may have been intensely private, but you can get a very good sense of who he was from listening to his lyrics, especially in late Beatles and his solo material. He bore his soul. He's more or less singing his values and experience (which he usually confirmed when asked in interviews).
Bowie let very little of himself out in his lyrics (at least not directly). Bowie seemed to know others better than he ever knew himself. He didn't bear his soul so much as he bore his emotions. Take "Heroes", which despite being regarded as an anthem, is really, at its heart, a love song about two lovers in Berlin. He's singing more through characters in his songs, he's singing about the human condition reflected through his perspective, and from there, it generates a great capacity for emotion and expression in his music, whereas it's almost the opposite of that with Lennon. Lennon relied more on his own emotions and values to muse and reflect on the human experience. I think an INFJ better understands themself through how they understand others, and it shows in Bowie's music. I think an INFP better understands others through how they understand themself, and it shows in Lennon's music. They're going for similar goals, but via different routes.
When Lennon showed his socially conscious side, i.e. with a Bed-in, even though some may have balked, his fans generally adored him and idolized him. I think it was a very frank and honest expression of his values when he spoke his mind. And he didn't give a shit if it offended. Whereas Bowie showing his socially conscious side maybe seemed more awkward and artificial, no matter how sincere he was. Seems a pitfall INFJs sometimes face. People didn't want to worship Bowie for being socially conscious, they wanted to worship him for being a rock and roll messiah. Although Lennon faced a similar unwanted worship as a pseudo messiah figure.
It's interesting to note Lennon and Bowie became good friends in the mid 70s, and it's my impression that they fascinated one another, as they likely sensed either had almost opposite ways of looking at the world and translating the human experience, yet they were both idealistic humanitarians at heart. I think Bowie's friendship with Jagger, OTH, was more primal and almost competitive, perhaps tying into both being Se users. Jagger tapped into that competitive, sexual instinct and brought it out a bit in Bowie. Jagger encouraged Bowie to embrace his sexuality onstage, but Jagger was always sort of ahead of Bowie in that facet, whereas Bowie probably encouraged Jagger to think ahead of the curve as an artist, yet Jagger was never quite as good at sensing the changing tides and remaining relevant and cutting edge as an artist the way Bowie could (with the obvious exception of Bowie's mid 80s output).