My day job is in high tech, so I've always had to deal with the divide between HR and the technical people I'd actually be working with. HR works differently at different companies, but usually they have two functions related to recruiting: filtering incoming resumes and doing actual active recruiting. In a lot of places, filtering is a checklist process. The technical staff says they want somebody with a particular list of skills and experiences, HR walks down the resumes and selects the resumes with the greatest number of hits. Obviously, this is a pretty superficial process, but if you can't get past this gate, you're out of the game.
By far the biggest ace you can hold is to have a friend on the technical staff who can suggest to the HR people that they really want to see your resume, bypassing the buzzword checklist.
If your resume passes the sniff test, there's often a phone screening where somebody (could be HR, could be technical) tries to validate that your skills really match the resume. Only then do you get scheduled to come in for an actual interview.
Active recruiting at larger places is often outsourced to professional head-hunters, who fill a lot more positions than just the executive suite. However, the last time I got hired, I got the call from an in-house recruiter. 30 years ago, companies ran job ads in the Sunday paper classifieds. No longer, but HR will post job ads on-line in various places.
During actual interviews, I've seldom had much to say to HR people, who are mostly there to discuss benefits (which have never been negotiable anywhere I've worked). Maybe HR tries to gauge "corporate culture" fit, but that's a pretty low priority most places. Most of my interview time is spent with the people I'd be working with, the hiring manager, and maybe one non-team technical person.