The irony is that multicelluar life is mindboggingly hard (probably harder than creating life itself, based on the current insufficient data) yet for us it doesn't seem that hard to cooperate.
Also remember that modern life has had billions of years to develop to the current life forms. Any primitive cell structure would not survive until today, or survive for long if created today.
Drone, the significant advantage coal have is that it can easily bind to 4 different atoms and also easily form double bonds or higher. Silica for example doesn't form double bonds as easy. So while non-carbon life cannot be ruled out, carbon is definitly the most flexible molecule when it comes to create chains and advanced molecules.
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