The speaker in "To a Skylark" doesn't give us many hints about who exactly he is, in the most basic sense. (Actually, we don't even learn if it's a man or a woman who's talking. To keep things simple, we'll stick with the tradition of referring to the speaker as if he or she is the same gender as the poet.) We don't learn much, for example, about how old he is, or what he's wearing, or if he's rich or poor, etc.
We do know that he's a poet, or an artist of some sort. We also get a ton of info about how he's feeling. Our speaker is one sensitive dude. (Being poetry lovers, we should point out that we here at Shmoop are big fans of sensitive guys.) He feels and sees and thinks about things deeply and intensely. He tends to be a little melancholy, a bit of a pessimist about his life and his art.
But he's also full of passion and love and hope, very much alive to the world. That's important because this poem is all about feeling, about the way that the natural world can create joy or sorrow in us. Our speaker's job is to talk about what he sees and hears, but also to try to make us feel exactly what he feels.