I'll add a few things.
Remember that largely there is no law or regulation that specifically says who can or can't and who should or shouldn't be bumped, nor the order or criteria that a carrier must or may use to decide who will be a bump.. Largely so long as they ask for volunteers and compensate/reroute those who are bumped, they have huge discretion in choosing.
As noted a later (but still legal) check-in person is more likely to be bumped....
I all add that carriers also give consideration to the following:
A) Are you a 1-of-1 or part of a larger group? If the carrier needs only 1 bump, there're less inclined to bump a person who is a part of a 2+ person booking..
B) Bags.. While most folks on long(er) haul international have them, they do give consideration to the question of how many bags does the passenger have? Each bag takes time to find and retrieve from the baggage container or aircraft (if non ULD movement) and for the carriers, the fewer bags a prospective bump has, the easier it is to bump them from a ground handling perspective, and the more likely it is that can complete the bump process and still make on-time departure.
C) Where are you going? Since carriers have to still get you there, they do give consideration to your final destination. They're more likely to bump someone who can be rerouted easily - like a large(r) city that may have multiple flights of multiple routings that will get you there reasonably quick. In the same vein, they are less willing to bump someone who is going to a city that has few(er) flights like 3x weekly and with few or no, alternates.
Item "A" also plays into this as if they bump a party of 2+, they have to find space for both..
My suggestion is if you want to be bumped, let the counter agent and/or gate agent know. They're the ones (more the gate agent) who will be aware of and administering the bump process itself.