Multicellularity seems to have evolved multiple times independently
This isn't really true. Only organisms with mitochondria developed multicellularity. Mitochondria are the hard part.
eusociality developed in aphids, thrips, mole rats, termites, and at least 11 times in Hymenoptera
Similarly, it would be more informative to say that Hymenoptera developed a particular pattern of chromosomal inheritance once, and that led to 11 different types of eusocialism.
We have a sample of one modern human civilization, but there are some hints on how likely it was to happen.
Major types of hints are:
Data for:
Data against:
To me it looks like life, animals with nervous systems, Upper Paleolithic-style Homo, language, and behavioral modernity were all extremely unlikely events (notice how far ago they are - vaguely ~3.5bln, ~600mln, ~3mln, ~200k or ~600k, ~50k years ago) - except perhaps language and behavioral modernity might have been linked with each other, if language was relatively late (Homo sapiens only) and behavioral modernity more gradual (and its apparent suddenness is an artifact). Once we have behavioral modernity, modern civilization seems almost inevitable. Your interpretation might vary of course, but at least now you have a lot of data to argue for your position, in convenient format.