Are you perhaps a
Seed?
Many people don't put a high value on me,
Seed packets are super cheap, usually costing less than a few dollars.
even though I have more potential than most.
There are many seeds that can grow into many things from such a small object.
I have certain well-defined tasks to complete,
Seeds have many duties such as protection and transportation to ensure that the embryo within is safe and can grow.
but if I complete them all, then watch out!
If the seed can protect the embryo, then it will start to sprout. I guess it's exciting to see the first signs of germination?
It's true that I'm smaller than others,
Seeds are indeed small.
but pass by me at "5 o'clock" and you might pay.
Not sure about this. There are plants called "4 o'clock" flowers, but I've yet to find a correlation to this line.
It's true that I'm slower than most others,
Seeds take a long time to grow, roughly 10-21 days.
but I've never reverted any of my decisions.
AFAIK, seeds can't reverse their growth :P
Even when I cannot physically move forward,
Seeds cannot move without some kind of aid.
I do everything I can to fulfill my duties.
As mentioned above, protecting the embryo.
My siblings and I help each other succeed,
Some seeds will travel and grow together.
But few reach enlightenment and are transformed.
Only seeds that have the right conditions can grow and transform.