Why does Skyrim number all game saves in order?
We had save number 25 so we erased all saved games (including the autosaves) to start with a blank slate, but when we started a new game and told it to save, that save was saved as number 26.
How can we reset it so it starts at save number 1 again?

I don't know honestly. I'm not sure you can if your on console, don't know about pc.

I wish you could just name the saes, because just having numbers is very annoying. Especially the more characters you have.

Manually go into your saves folder and move the saves for your other characters elsewhere while you are on another character, this avoids all chance of confusion and accidental overwriting of saves (And resets the save # to 1).

you can also rename the saves manually.