I do think there was a bit of undecisveness in what direction to go in. After showing that murial with the mysterious green stone, I would have preferred if the focus remained on that in regards to the origins of the xenomorph.
Instead, they went the pregnancy route, and while it did produce one of the best moments of the film, thematically it was forgotten about. I think yourself pointed out how no-one asked Shaw what had happened after collapsing in blood and I also found that absolutely maddening. So yeah, while the c-section scene was a highlight, it was very much a set piece and its only contribution to the plot in the end was to give us that tached on ending.
I just remembered another highlight; the moment Shaw got in the engineer's face while Weyland was telling her to shut up. That was great. I really wish they had dedicated more time to that whole moment rather than wait for a sequel that may not happen.
