Personal experience of a human being is the moment-to-moment experience and sensory awareness of internal and external events or a sum of experiences forming an empirical unity such as a period of life.
An early belief of some philosophers of Ancient Greece was that the mind was like a recording device and simply kept somehow-objective records of what the senses experienced. This was believed in the Western world into the 20th century until cognitive psychology experiments decisively proved that it was not true, and that many events were simply filled in by the mind, based on what "should be". This, among other things, explained why eyewitness accounts of events often were so widely varied.
In Ancient Rome it was believed that personal experience was part of some divine or species-wide collective experience. This gave rise to notions of racial memory, national mission, and such notions as racism and patriotism. It was likely easier to create political movements and military morale with such notions, than a strictly personal idea of experience. Carl Jung and Joseph Campbell were notable investigators of these ideas of collective experience in the 20th century.
During the Enlightenment, there was rigorous investigation of these ideas. Immanuel Kant noted that it was only possible to explain "experience and its objects" as a consequence of each other: either experience makes those objects possible, or those objects make experience possible. This is seen today as dualism, and denying the possibility of a third thing making both experience and whatever reality its objects have, both possible. That thing could be a more universal cognition, as proposed in some versions of Christianity or Gaia philosophy.