I will assume creatures means animals.
Six letter animals:
six letters long
Smurfs is six letters long.
toward
alpacabeaverbobcatcougardonkeyferretgibbonmonkeypoodlerabbit
JehovahAnswer:Both Lord Vishnu and Lord Brahma have six letters in their names and were creator deities.
walnut
minute
Author
Carats.
Pigeon
Another word for "succeed" that is six letters long is "thrive." It conveys the idea of not just achieving success but also flourishing and growing in a positive manner.
The middle of a word with six letters is often referred to as the "third" and "fourth" letters, since they occupy the center positions. In a six-letter word, the middle letters can be considered the heart or center of the word. If you're looking for a specific term, "center" is a fitting descriptor, but it is not six letters long.