What wood is our floor made from and will it be good as polished boards?
Meta-answer:  (Not an answer, but pointers to where you can find one)

Find the year of construction.

Find a builder that was active during that era.

Show him your picture.



That said:  It looks like you have damage or rot on one board.  I'm puzzled by the light streak toward the bottom (picture) of many of the boards.
Some softwoods are suitable for flooring.  Larch heartwood works well, as does douglas fir, once it's about 5 years old. Some hardwoods do not work well, either because they are too soft, or don't sand well.
You can check for hardness by getting a sample of wooden flooring from a floor store, and see what height you have to drop a medium size rock on it to produce a dent in the wood.  Now repeat that test with your uncovered floor.  (The actual test is with a spring powered thingy that you snap, and then measure the depth of the ding.)
If the wood is porous you can improve the hardness somewhat with WEST  Wet Epoxy Saturation Technology. This uses a slow cure epoxy that soaks into the pores.  Normally used as a boat construction technique along with thin layers of fiberglass or kevlar.