divers? was that supposed to say "divots?" Are there actually documented cases of someones skull deforming from wearing headphones enough? I have never heard of such a thing.

Headphones are not leaving divots in anyone’s skulls

They would be amazed on how we were able to survive for so long with our balls full of microplastics.

Divers wearing headphones? Regardless, I suspect that after a million years there won't be much left of the headphones.

I think headphones aren't tight enough to leave divots, but cochlear implants might make them wonder.

What the title says doesn't make sense! Divers?

No, I don't think headphones will changes the skull, unless you put them on a newborn. But I do wonder how much information could be lost, given how much of it is digitalized nowadays.

Of archeologists don't know it: "for religious reasons".

I expect them to dig up people with curved pinkies due to holding phones all day

yes

1. If the civilization that discovers it is more advanced than 20th century humanity, then no. They would know their purpose.
2. If it's not as technologically advanced, the it's possible I suppose