One of them is the precise role granted to non-humans. They have to be actors (see the definition on p. 64) and not simply the helpless bearers of symbolic projection.
I could say that ANT has tried to render the social world as flat as possible in order to ensure that the establishment of any new link is clearly visible.
It is visible only by the traces it leaves (under trials) when a new association is being produced between elements which themselves are in no way ‘social’.
‘social’ is not some glue that could fix everything including what the other glues cannot fix; it is what is glued together by many other types of connectors