In all other competitions I've seen, still & animation were a separate category. An animation requires much more work than a still and it's a different product. Thus the two cannot be judged with the same conditions, and shouldn't be in the same category.
For more affluence next time consider more topics the participants could chose from and also categories for pro & amateur renders (like DayVids mentioned above). Also, the competition cannot be left unmanaged by thee organizer, like this one was - the organizer should motivate & antagonize the participants and closely observe the competition development. And respect your own deadlines & rules you set at the start.
An competition should always have a topic (or more of them), because it's more challenging & fun this way.