Image opens fine for me in Gimp (2.10.34).
When I open your image, it is an indexed PNG. The spider is black and black is often the default color to mark transparent things. Further more the colormap contains many instances of #000000, which seem to correspond to anti-aliasing pixels on the edges. These pixels are partially opaque so may be the color indexing is really to RGBA values.
Edit: so yes, in a PNG the color map entries can have an associated alpha, so it makes sense to have several #000000 entries, each with its own alpha value.
When I open your image, it is an indexed PNG. The spider is black and black is often the default color to mark transparent things. Further more the colormap contains many instances of #000000, which seem to correspond to anti-aliasing pixels on the edges. These pixels are partially opaque so may be the color indexing is really to RGBA values.
Edit: so yes, in a PNG the color map entries can have an associated alpha, so it makes sense to have several #000000 entries, each with its own alpha value.