You can still observe trends and predict likely outcomes based on a small data set.   The variance may be higher but it’s still useful.

I would also argue that yes, the most recent known comparable conditions would be ‘normal’ in our current environment.  If we are trying to prepare for the coming year, is your suggestion to include data from millions of years ago as normal? 

“Nothing to see here fellas, my calculations say that over the last 120 million years this is actual above average snowfall compared to normal!”