Life needs a few things to start and various others to continue. The list as we think about it today for organic life would include water, temperature, nitrogen, an absence of things that would kill life, and sunlight. Being in a habitable range from the solar system's star gives the right temperature, atmosphere provides the resources needed for movement, not having things like radiation or constant asteroid strikes allows for life to continue, and sunshine is a key source of energy needed for all organic processes. Over the timelines which form planets as earth has been formed we would expect many different paths. The things we do not yet understand or perceive about how life exists in general are likely to also shift what we can expect to be the actual standard since we do not know what might be missing from our understanding and thus can not adjust. The earth is like a garden on a spit basking in the eons of energy flowing from a constant fusion engine millions of miles away. Estimates placing the age of life on earth going at least as far back as 4 billion years and the sun as being at least 4.5 billion years old means an astoundingly long fire with much more time to shine.
What moves life on our planet today is all of the things we have named but there are examples outside the forms we consider typical. Deep in the ocean near hydrothermal vents that spew super hot water live creatures that rarely if ever see sunlight or vary the type and amount of things needed on the list above. As we search for life in the recesses of the galaxy we often focus on forms, origins, and timescales similar to those we imagine for our own. Yet the possibility for others much different from our own is great. Planets covered in ice but fueled by the internal energy of their core could be eccentric rogue cauldrons for life unseen. The millennia of isolation we feel brought life to the point it has reached would be in stark contrast to that seen by such rogue planets. The creatures on our planet that can go generations with no knowledge of the sun give examples of how those forms of being on possible rogue worlds are seen today. There is harmony represented on Earth in various forms and many layers.
The transition is where the danger resides for life as we know it. The threat of nuclear winters blocking out the sun and reducing life to a struggle to persist has been explored in part through novels and film. Often seen as dystopias, we quake at the thought of the reduction of resources on which we rely especially in regards to our longest most consistent solar supporter just over 8 minutes away by light mail. The warmth given by stars is a feeling held differently based on the needs of life. The creatures needing no sunlight surviving on the edge of what we know to be sustainable would need no change were the sun to change roles or become more distant. The harmony holds a baseline through the representatives surviving on the edge. The forms seen on these sides can feel harder to appreciate with general ideals of beauty. Scavengers at the ocean floor, simple cell organisms, and a much less forgiving sphere of life feel harder to connect with in the usual way. What we express in connecting is a reflection of the standards of being we hold dear. The dystopias we envision offer a chance to view the selves subdued by a world of plenty. What we become with little is tied intimately to what we embody in much. The beauty in resolve radiates and can deepen our appreciation for what is possible. Life would be much different were we on another planetship careening through the universe unbound by a star touring the universe with millions of years between passing visits, galaxies of untouching billiards with life within. Come what may we see possible in layers. To continue expanding it is helpful to appreciate what we become in times of little and think what is possible then that is often unseen.