What is an ode? Critically analyze Keats as an ode writer

An ode is a form of poetry, usually rather short, that generally praises a person or subject (such as nature). It may also be contemplative. The overall tone is serious. Technically, it may use patterns of rhyme within the stanzas, but there is considerable leeway in the structure that can be employed. Those that do not strictly follow fixed patterns are called "informal odes," which is the type that John Keats and other Romantic poets generally wrote.
During his short life, John Keats wrote several odes that have become acknowledged as masterworks of poetry in the English language. These include the odes to melancholy, a nightingale, and Psyche. His love of beauty and ardent desire for both the artistic spirit and adequate talent to express his emotions are driving forces behind his impressive creativity. At the same time, his consciousness of the difficult task he has assumed and his worries about failing in this mission, as well as concerns about mortality, often invest his works with a dark, somber tone.
The "Ode to Melancholy" notes the contradiction between positive and negative states. Among these is the exaltation of Beauty and its short duration: "She dwells with Beauty—Beauty that must die." Meditations on mortality dominate the "Ode to a Nightingale," in which he addresses the bird that sings in blissful, ignorant freedom while he, as a man, is always aware of mortality in a world "Where youth grows pale, and spectre-thin, and dies." His own flight will be "on the viewless wings of Poesy." In the "Ode to Psyche," Keats dwells on the poet's role, imploring the goddess to let him serve her.
https://literarydevices.net/ode/