The whole question of the jump from non-life to the simplest known
bacteria has left me wondering about what would constitute life
_simpler_ than that of a bacteria, or more basically, what would the
"primordial soup" out of which bacteria or first life would have
spawned.

A bacteria has a membrane that separates itself from its environment.
It is also capable of replicating itself.

A compost pile, in contrast has no clear boundary separating its
environment, but it can grow over time. Could it be useful
conceptionally to "dumb down" the definition of life or protolife to
basically a self-perpetuating process?

Granted, _today_ a compost pile (or soil) contains all kinds of
bacteria within it, but perhaps the "primordial soup" have been
basically a bacteria-less "compost pile" that even without bacteria
grew in size and complexity over time.

Even simpler examples of self-perpetuating phenomena include fires and
storms.