General:
* A tapestry of life: Emphasizes the intricate and interconnected nature of life.
* A spectrum of life: Highlights the diversity and range of living things.
* The web of life: Focuses on the interconnectedness and interdependence of life forms.
* The miracle of life: Emphasizes the awe and wonder of existence.
Specific:
* A swarm of life: Could be used for a large number of small living things.
* A throng of life: Suggests a dense and bustling group of living beings.
* A multitude of life: Indicates a vast and diverse collection of living organisms.
Ultimately, the best collective noun for "life" depends on the specific context and the impression you want to convey.