it appears to be varnished pine. I can see three boards that have been cut short at the same point. Probably by a plumber or electrician. And one with a lump missing where it has been pried up.
Most likely your creaking boards are the ones that have been taken up and put back with insufficient support. Probably adding a strut (noggin) or sister to the joists to support the cut edge will do it. If they are screwed down it is easy to take them up, but they are probably nailed down.
You can see the rows of nails which indicate the centres of the joists.
I favour retaining original features of the house.
Both your options involve taking up the old ones.
I favour rectifying the defect and then putting them back down.
Proceed with care because there are most likely pipes and cables cut into notches in the joists, probaly under the boards that have been lifted in the past. Try not to saw, drill or nail through many of them.
You can also repair a cracked or broken floorboard if you can be bothered to spend a bit of time and have the pieces.
If you are weedy, a carpenter can do it but will probably want to work quickly and not bother with retaining or restoring originality. an old one who is a slow worker will be OK because it is a very small job. You will enjoy hoovering out a hundred years of dust, cobwebs, dead mice and builders rubbish from under the floor. Use a canister or workshop vac if you can get one.