I've found a lot of discussions concerning refinishing antique (100+ y.o.) flooring that have been VERY helpful, but I have a couple specific problems that I'm hoping someone can help with.

Just bought a 1907 house w/ original (varnished, I think) flooring. It's been sanded too much to sand again, so a total refinish is out of the question.

There are major scratches that are black with grime and substantial wear in some places that is grey and extremely worn. The floor is pretty uneven also.

Here's my plan: Clean up all the scratches/gaps, scuff up the flooring, put on some Waterlox.

Questions:
Is that good enough?
Will the difference between the heavily worn areas and the lightly worn areas be noticeable/drastic after finishing?
The scratches are pretty deep and black. Is it possible to make them look good without sanding?

I don't want the floor to look perfect and new, just better than it does now.

Any help is appreciated! Thanks a lot!