Replace or supplement very old attic insulation
That insulation is most likely what  my father-in-law bought for his home in the 1960's. It was called &quot;pouring wool&quot;, sold in bags and was very itchy. I was dating his daughter, now my wife of 58 years, and I offered to install it for him. (you can guess why). We did the job in JULY. I wasn't too smart back then. It looks just like that . I would just install batts over top of that insulation. Make sure that you do not cover the soffit vents and do not fill up into the roof joists. They have styrofoam vents that go between the roof sheeting and the insulation. Good luck.