It's still an open question how life formed from non-life(look up abiogenesis).

It's also an open question whether it formed on Earth at all or came here from elsewhere.

So there is no answer to your question as yet. Or at least there's no scientific consensus on one.

We know DNA and and even semi self replicating biochem molecules can form both in the presence and absence of gravity. It requires a suitable energy gradient though, and I like the idea that cyclical changes in the energy gradient are required for evolution to occur rather than stagnating in a specific state. This is partly why tidepools are an interesting candidate for early life.

I think the closest to a 'low gravity' environment is the oceans. So I suspect yes, life would form in low gravity environments. It would likely have more rotational symmetry vs mirror symmetry land animals have. You see a hint of that in ocean life where things are more...round.

Now you've got me wondering - what is the difference between buoyancy and low gravity (with respect to organism development/evolution)? Would there be any meaningful differences structurally?

I would think yes. In a submarine, the vessel is buoyant, yet the contents are subject to regular gravity. I think the same reasoning applies to a body and its organs and fluids. Contrast with space where everything floats.

> I think the closest to a 'low gravity' environment is the oceans.

The oceans are not a low gravity environment, and gravity is no less when floating in water. Depending on the density of the water and the object that is floating, it is buoyancy that causes floating in water. Gravity works the same on the floater and the water.

And we could correctly assume gravity is essential for life, as without gravity, not even the Earth would not revolve around the Sun, let alone whatever it is that life is supposed to form on in low gravity, and we know that light is essential for life.

Most sealife has mirror symmetry though, doesn't it?

I guess jellyfish, urchins meet the rotational symmetry though.

That’s about aerodynamics (hydrodynamics?), as water is more resistive than air.

it's pretty certain that life in this form would not have formed without gravity though.