> If you don't have Covid
That's a big "if". When's the last time you were tested?
Because that's the actual reason to wear a mask. Preventing yourself from getting infected is less relevant than preventing yourself from infecting others.
> A passing squirrel or a bird is not going to infect anyone.
I don't know about those two animals specifically, but it is very much possible for COVID to spread via animals (that is, indeed, in all likelihood how the COVID pandemic started in the first place).
> People walking solo in open spaces with masks on - which I see a couple times per week on my morning run - perpetuates a scientifically false narrative.
No, it perpetuates a narrative of "it's better to be safe than sorry", which is about as scientific of a narrative as it gets when it comes to infectious diseases. I wear my mask when out walking or hiking specifically because I don't trust others to keep their distance, and because I care more about the possibility that I might inadvertently spread COVID to someone who'd die from it than I do about messing up my beard with a mask.