I think it's safe to say, that most of my working life for now I've worked with CI-setups. Mostly developing custom software for CI and deployment related tasks and solved such problems.
CI is wide. It's vast as a concept and even more large in practice.
It's also rather simple, and serves one damn important purpose.
It's a seal of trust
Between programmers working on same code-base.
And that's as simple as it gets.
Basically we share a common contract of not breaking shit up. Surely, we want to get stuff done, but while at it, we really, really don't want to break stuff up. That should be the most intrinsic trait among us, that should be the animal in a developer. The ghastly aura of "This doesn't feel right".
Yet we do. I do.
Thus I need a tool
To make sure that other people won't pull my fuck-ups. Surely we test before push, but still you don't exactly know what other people actually do. Thus we need a queue to keep things in line.
It's not a mechanical, dummy build machine you know. It's the guardian that keeps you on keeping you promise to other developers.