Why Is Buddha So Important?

Maybe you mean, The  Supreme Buddha, Siddhartha Gautama.
The word "buddha" means "one who has achieved bodhi." bodhi is also frequently (and more accurately) translated as "awakening," Although its most common usage by far is in the context of Buddhism, bodhi is also a technical term with various usages in other Indian philosophies and traditions.
Bodhi is an abstract noun formed from the verbal root budh (to awake, become aware, notice, know or understand,) corresponding to the verbs bujjhati (Pāli) and bodhati or budhyate (Sanskrit).
en.wikipedia.org

Its not important