I’d (idiosyncratically) consider Thales’ pupil Anaximander the first philosopher, as we understand ‘philosopher’ today, and consider Thales more the ur-scientist. From what little information remains about them, Anaximander’s doctrines were more traditionally metaphysical than Thales’, and he was a deeper and more systematic thinker; we also have a single line of actual prose from him, the oldest extant piece of philosophy in human history (excepting maybe some stuff from the Upanishads).
I’d (idiosyncratically) consider Thales’ pupil Anaximander the first philosopher, as we understand ‘philosopher’ today, and consider Thales more the ur-scientist. From what little information remains about them, Anaximander’s doctrines were more traditionally metaphysical than Thales’, and he was a deeper and more systematic thinker; we also have a single line of actual prose from him, the oldest extant piece of philosophy in human history (excepting maybe some stuff from the Upanishads).