Your life isn't of much significance; there have been billions of other humans in existence, throughout multiple epochs and countless places. Very few of them have changed the world in any palpable way, and even for the ones that have changed the world in a significant way, the fact remains that humans occupy an infinitesimally small part of a gargantuan and indifferent universe, living lifes of grotesquely short duration. However, your life is actually of incalculable significance. If you die the whole universe may as well cease to exist; your perception is reality itself. Which one of these extremes contains the most truth?

You describe two different standards for judging the significance of one's life. The first measures its significance by the size of its contribution to a long history that includes billions of other human lives. The second measures its significance by the degree to which it matters to oneself. One could quarrel about just how small one's contribution to human history really is, or just how important one's own life is to oneself, but the tension that is created between these two standards remains. Some philosophers (e.g. Lucretius) have recommended that we adopt the longer, more "objective" view, and cease to view our own lives as particularly important. Others (e.g. Sartre) have insisted that a truly "objective" view makes no distinctions between what is significant and what is not, for there is no value at all apart from the cares and concerns of a particular subject. Still others (e.g. Thomas Nagel) have suggested that human life requires us to sustain both of these irreconcilable perspectives ...