Here's a brief synopsis on Alien Anthology series so far and input about the BLACK GOO.

*Engie creates multiple chain of humanoids 
*Engie discover the creation of xeno from the black goo and praise their new superior creation but soon after they're all gone because of an outbreak 
*Prometheus happens
*After David gets lonely he learns about the xenos and engie's past aboard the ship (as shown in the prologue). He believed he can   perfect the trilobite/deacon creatures himself)
*Then he destroys the humanoids (not engie) on the planet thinking they are engies and doing it out of hate of the species he underwent in Prometheus. 
*Experiments with the liquid until he turns Shaw into the queen,
producing facehuggers (theory territory) 
*Later infects other organism or humanoids with the spores and facehugger
*Alien covenant happens

Black Goo AO-3959X91-15

What is it?
It is an extremely potent and virulent mutagenic pathogen, composed of millions of small micro-organisms, that was manufactured by the Engineers as a biological weapon, presumably for military purposes. It was derived from a life form know as Xenomorph. Due to its volatile nature at ambient temperature, the Engineers housed the pathogen within Steatite Ampules. The urns are like grenades, they need to be primed first. The Urn that David snatched was a dud that didn't fire when he and the humans entered the ampule room. This is evidenced by the many urns you see later on aboard the Juggernaut, which are set within a similar environment to the ampule room but did not react to the same atmospheric conditions. In order for it to be preserved it has to be stored in a moderately stable and cold environment however Inside the urns, the black goo is stored within those vials, one of which David examined. When the Urns are primed, the black goo is released, mixes with the surrounding material (the slime) and leaks from the urns

How affective is it?

Internal usage

The engineer in the opening of Prometheus ingested the goo and it broke his body apart and it did the same with Holloway but since he had a small amount it killed him slowly and since he slept with shaw the night before that caused her to give birth to the alien.

External usage

Exposure to the liquid externally has a more diverse affect as it reacts differently to a host depending on the atmospheric surrounding. In the ampule room where the urns were slightly combusted/primed due to a change in the atmosphere. The host exposed will succumb to DNA alteration and is transformed to a weaponized aggressive being, as seen by Fifield.

If the urns containing the goo are met with a hot environment or high pressure they'll gradually combust and eventually explode spreading the goo. David deployed the steatite ampules over a large settlement, the pathogen reacts by petrifying every Humanoid present and drastically affecting the environment by exterminating or mutating non-floral organisms, giving rise to highly aggressive hybridized predators like the Neomorphs.