Choices occur at several levels of "Thirteen Ways of Looking at a Blackbird." At the most general level, the reader has a choice of thirteen ways to look at a blackbird. Do you find one way more compelling than the others? You have the power to accept or reject any of these perspectives. Stevens just wants you to know that you have options. At a more detailed level, the humans in the poem express indecisive behavior, though indecisiveness is not portrayed as a terrible thing. Choices are a part of the complexity of the life, and only the "bawds of euphony" would have it any other way.
"Inflections" and "innuendos" represent two different philosophical stances on the question of whether language can express truth.
Indecisiveness is not major theme in the poem.