first try some cheap chair leg protectors

but a thick rug under the table..wide enough to protect the floor when the chairs are pulled out might help as the floor won't be hardened by sanding but is it solid timber or laminate?... check with a flooring supplier for advice

Timber will dint. Change chairs to a thicker leg to reduce point load or add a rug to protect floor. May need a rug anyway. Remember dents add to character of a timber floor. At least I keep telling my husband that, not sure if he believes me yet. Funny how we are happy to see dents in a 100 year old floor as history but not newer floors.

Don't know if you have resolved "denting."

Flooring looks as if Baltic Pine If so it is the softest of all floorboards and dents easily.

Most homes of 1920s had a central carpet square, surrounded by Black Japan bare flooring, should you remove any carpet, this will be evident.