There are no beings, entities, or objects. This is a misunderstanding of how reality works. Reality is made up of moments of experience. Moments of seeing, hearing, smelling, tasting, touching, and thinking. Nothing else. These experiences are arising and passing away every moment. This arising and passing is samsara. The cycle of birth and death. When enough of these experiences happen we call that a life.
In order for there to be an end to samsara the four noble truths need to be known. Without a Buddha this knowledge does not arise. Once there is a Buddha and they are able to teach this knowledge the path is followed. But after some time this knowledge disappears until another Buddha arises.
A Buddha arising is a very rare event. Coming into contact with the Buddha's teaching is very rare as well. Having heard the Buddha's teaching and having the desire to practice is rare. Having the ability and conditions to practice are rare. Becoming fully enlightened is very rare too. This is why it is so difficult to end samsara. In reality we never know the next time we'll come across the Buddha's teaching so we should take advantage of it in this life while we can.