at first few words

the writer has been adverted that, during that early time, they possessed few distinct and mutually understandable words.  far fewer than now, anyway, though one has also been adverted to consideration of the possibility that, had they been able to put it at all in those days, they might have been more likely to have said 'less' rather than 'fewer.'

So nothing complex could have been said, or saying it would require inordinate neologizations or implausible timescales.  They may, of course, have had both.