According to Wikipedia, the Gaia hypothesis, also known as Gaia theory or Gaia principle, proposes that all organisms and their inorganic surroundings on Earth are closely integrated to form a single and self-regulating complex system, maintaining the conditions for life on the planet.
This means, all organisms constantly alter life. We have life on our planet since the conditions allow it. Since the conditions are suitable for life on Earth, there is life on Earth. The life on Earth itself ensures it’s own survival. All of this life, from the tiniest form to complex human beings, are like one huge organism that ensures the survival together.
The point being, if even one species becomes extinct, this threatens the total survival, since we are all interconnected. The part we can be proud of, is that our life helps the earth to keep alive and thrive in it’s beauty. The part we should be very humble about is that we a tiny part of something huge. All the years the planet earth has existed and we are only a fragment of that history. For me, this means, living in a way that is respectful and reasonable considering our role as a part of something larger than ourselves.
Lovelock has written many books if you want to read more of his theories. His last one was published in 2009, when he was 90 years old and still going strong.