I'm not sure if this is a literal or figurative composition but I'll do the literal meaning. It is true that many innovators have invented a lot of items, machines and the likes since the mousetrap. Technology does not rest, it gets better everyday. Even the said mouse trap has improved overtime, it's traditional mode is no longer applicable has it seems the prey is now acquainted with the trap, even the prey is becoming intelligent as technology is improving.
The mousetrap is always in a constant need to be developed, and it is. So, I cannot really point to one invention made better than mousetrap because there has been quite a lot.
The participation link:
@mariannewest/day-1858-5-minute-freewrite-wednesday-prompt-best-invention-since-the-mousetrap