Also, I'm skeptical that this will ever be marked resolved. Scientific consensus has already been reached that other life is likely to be carbon-based. That doesn't rule out other possibilities, but carbon is a likely choice.

So the acutal resolution criteria is more like, "once I've been convinced that there is scientific consensus" or some other under-specified criteria.

Yes. Carbon has fairly low molecular weight, making it quite abundant, and its bonding characteristics allow it to form large, diverse molecules easily.