I'd recommend prioritizing impact over "duties, interesting projects", especially quantatative impact e.g. "built widget that increased x by y%"
I'd also always include months
I'd also always include months
I just looked at my (out-dated) resume and, for my first two long-term jobs, I just put the years, one of two specific titles, and a list of major accomplishments.
That said, I've never had to go through an HR screen so my resume probably never mattered much.