Redundancy protects against uncertainty and shocks. Then, unsurprisingly, you'll see redundancy all over biology, as we are observing those organisms that survived uncertainty and shocks. Here are just a few ways nature creates redundancy:
We talk of degeneracy when two parts perform different functions under normal conditions but are capable of doing the same function when needed. So degeneracy is nature's way of ensuring the failure of one part doesn't doom the entire entity.
We have an extra pair of some organs, which is a form of redundancy: if there is a loss of one eye, we still survive. While degeneracy refers to parts that perform different functions in normal conditions, an extra pair performs the same function all the time.
Functional equivalence is like an extra pair, but in ecological scale. Multiple species share the same function, so the loss or weakening of one species won't jeopardize the entire ecology.
I find it telling that nature has not just one, but multiple levels of redundancy. If we are to survive long-term, we ought to add redundancy to our lives, to copy nature (biomimicry is the term).
There are many more concepts in my "Mind Expander" tool (it's free)