Why do we assume disproportionate self-importance?

The planet earth is considered to be approximately 4.5 billion years old. It is estimated that out of these 4.5 billion years, 90% of the time there has been an existence of life. Not human life, but some form of life in the initial stage. Recognisable humans emerged about 2 million years ago on the earth.
It is evident that whether the creation of a giant planet or the tiniest microbe on a small planet within this big universe consisting of millions of galaxies, everything is formed out of molecules and turns into molecules at the end. The shape, size, appearance and energy of every aspect of existence take shape with time, change from time to time, and transform again at the end time of disintegration. A pertinent question to ask is what could be the relative importance of our planet earth in this giant scheme? And what would be the significance of the existence of an individual whose life is not even one century on this one planet earth? It does not exist for even a blink in the history of millions of years, and in the remotest place in the whole universal space.
Then why do we assume disproportionate self-importance and create a burdensome identity that crumbles us under our own ego? Does this ring any alarming bell in your mind? The bitter reality in front of us is that we couldn't take care of this one planet during our lifetime. In the last two to three centuries, there has hardly been any individual who has contributed to the betterment of the planet. Whether we consider the health of the soil or the water body or atmosphere, everything has gone worse from bad. Equally disappointing is that our relationship with each other has also not been a good story. Human
beings have been fighting wars in an attempt to establish supremacy over the resources which do not belong to them. There have been struggles with nature, and with other co-existing lives on this planet. It is time to realise our insignificant existence and learn to co-exist with other components of the universe coexist peacefully.