Very unusual to find a mixed species floor. Obviously, the flooring was never intended to be used without being covered...hence its use as an underfloor. If you think you'll be happy with funky/quirky, then refinish it. After all, it's your house.

Without seeing the floor in person it’s hard make a
judgment, however there are few things I was able to catch in addition to
different species you mentioned. Gaps between boards are fairly large and with
different wood species they will work differently with humid and temp changes,
so your gaps might get even larger. Another issue I find with refinishing
floors Is, that it will never looks as good as new. If it was my floor, I would
replace with same type you have throughout the rest of your home. It’s a small room
so the cost difference between refinish and new should not be that big.

Refinish it. its a small job and worst case scenario you tear it out later, or put something else over it (dealing with a height issue then)

Looking at the adjacent rooms in the bottom left and right, it looks like oak floors surrounding this room. Have them pull up the pine and put down oak then finish to match for a continuous look would be my vote. If they could stagger the seam at the bottom right that would be good too.