I suggest
If it can reproduce and mutate heritably, it's alive.
I find the idea that viruses aren't alive ridiculous.
Is an infertile animal (which can't reproduce) dead? What about a nerve cell (which have differentiated too far to become a reproductive cell)? Or a red blood cell (which has no genome)?
From the other end, is a genetic algorithm alive? What about a manuscript? Manuscripts are copied (so they reproduce), and have frequent copying errors, which propagate.
Machines fit this definition.
Fire fits this definition.
Truth is "life" is not a distinct category. We just think of life as complex life. A complex system that mines energy gradients to preserve and replicate its forms.
But there's no hard boundary. It's just in our head.
People always come up with people-centric definitions. They need to be updated based on what are the fundamental characteristic of something that is alive.
The current, more standard definition, seems to be based on metabolism. I disagree and argue for reproduction and evolution.
Crystals can "reproduce", but it's always the same (there can be errors, but they don't inherit), so they don't count.
And atoms don't reproduce, so I'm missing your point there.
You could say "they have no heritability", and not the way you expect, I guess, but they all inherit the same local laws of physics, and they may even impact those laws, thus forming a feedback loop, and clearly there are googols of them in clusters, same weight, same energy, same polarity, same properties, same states, much like you see with any other species in nature, in fact in far lesser numbers.
If robots are made in a factory, does this count as reproduction? If not, why not. Does a mother's womb not resemble a "baby factory". A baby does not create itself. Always something else creates you.
We have clusters of "common sense" about these things, and most of what I said immediately sounds stupid to "common sense". Yet common sense falls apart if you start thinking about it. But Internet is not EXACTLY conductive to "thinking about it". It's all about the hot takes and the current consensus. Then time passes, and that consensus seems truly unenlightened.