The liquid isn't really a liquid, but a soup of fairly tightly bound microscale multipurpose components. Not nanobots, but the insides of these artificial cells certainly make use of nanotechnological processes.
Each component (let's call it a "souplet" with a nod to the components of utilty fog). They're relatively dumb and simple things... they contain a small power source and a very small and simple processor, a tiny fleck of memory and a few molecular motors attached to arms which they can push out and retract to some small degree. Each arm also has tiny data and power connectors. Individual souplets can't do anything; they're too stupid. When you've got a critical mass though, you can program them to do useful things, like link up with other souplets to form a power and data network, form into a useful shape, wander around, squash meatbags, that sort of thing.
This is obviously a fearsomely powerful technology, but you need a correspondingly fearsome computer to drive it in any useful way. If your computer broke, or you lost your souplet fabricator but left it turned on, you get a load of fairly unintelligent amoeboid things that floop around in a fairly aimless way. Maybe they bump into the debris of former souplet aggregates who met an untidy end, and absorb a little tiny bit of the programming and memories of the fallen. Something about being human shaped? Yeah, that'll do. Close enough. I'm sure the rest of the programming directives are in another bit of you somewhere near by. Maybe those other human looking things. Lets network with them and see what happens.
The periphery of the souplet network can provide propioceptive information. The centre which doesn't have to move around can supply electrical and processing power for the periphery. The bits that don't need to move much can become denser and tougher, a bit like a skeleton (but perhaps more like the trunk of a tree).
You slice one of these things in half, and the two halves have suddenly got a lot less intelligent, individually. Throw em off a cliff so they go splash and the resulting puddle can't really do anything useful except slosh about trying to reaggregate and work out what it was and what it was doing before it was so rudely interrupted. This looks like regeneration but is really just repair and repurposing. Destroyed souplets stay destroyed. Heat, corrosion, radiation and or merely suitably applied mechanical force can destroy a souplet. The aggregates can be ground down and indeed killed. But if you don't do a thorough job, the next aggregate that comes by might step in a splash of the one you didn't quite kill enough, and remember a little bit about you, and how it doesn't like you very much, and how you might be a bit less on guard now...
