Jobim was a serious composer who happened to write melodies so smooth and effortless-sounding that people mistake them for simple. They aren't. Listen closely to the chord changes under "Corcovado" or "Insensatez" and you'll hear someone who studied Villa-Lobos and Debussy and figured out how to smuggle that harmonic sophistication into a three-minute song about heartbreak.
He grew up in Rio, played piano in nightclubs, and by the late 1950s was writing songs with Vinicius de Moraes that became the backbone of bossa nova — deceptively laid-back on the surface, full of extended chords and unexpected turns underneath that jazz musicians immediately recognized as kindred material. When Stan Getz and João Gilberto recorded Getz / Gilberto (1964), American audiences finally caught on, and Jobim's tunes became standards covered by everyone from Frank Sinatra to Bill Evans.
What makes his writing durable is that the melodies work no matter how you dress them up. His own recordings, like Wave (1967) or Stone Flower (1970), favor restraint over showmanship, letting the compositions and often-gorgeous arrangements carry the weight. Bossa nova at its best is about understatement, and Jobim never abandoned that even as the genre got commercialized into background music.
He gave jazz musicians a whole new set of harmonic puzzles to solve, wrapped in melodies warm enough that nobody minded doing the homework. Full catalog on his artist page.