When we bought our house in 2000, it had been vacant for a while, and people had gotten into the habit of walking across the lawn from the railroad bed to the street or vice versa, so when we first moved in, despite our cars being there, we'd often see people walking across our lawn. When kids do something like that (or pick flowers from a garden), I'm more tolerant because kids, young kids especially, don't always understand or care about boundaries, but adults were doing that. So, for a while, I put up NO TRESPASSING signs, and eventually that ended that problem, for the most part.
I generally have game cameras up on trees and elsewhere in the back yard, but those are ones that I have to collect the SD cards to view, and they are mostly there so that I can see what animals (cats, foxes, raccoons, skunks, fishers) are coming into the yard. They did pick up on one person, who appeared to be in his early 20s, perhaps, come into the yard from the railroad bed, tried the door on my outbuilding, which is often left unlocked, but was locked at that time, then left. But the camera that picked it up was too far away for me to recognize him. In the front, we have a Ring camera, so we know who comes by. We don't usually have it on alert, though, because I feed cats on the porch, so there are always cats (and sometimes raccoons) going in and out. The raccoons come only at night, and I am usually in my office downstairs, so I run them off and pick up the food before going to bed, so as not to encourage raccoons.
I have found four arrows in my backyard, so I assume that someone (probably a kid) in the next block over has a bow and arrow target set up on the back fence, and occasionally overshoots it.