This interlude in G major is composed in simple binary form with 2 periods of 8 measures each. Measures 1-4 form a question (ending on the dominant) and measures 5-8 - an answer (ending on the tonic).
Measures 9-12 feature the same rhythms but often inverted intervals with the modulation to the dominant key (D major). Measures 13-16 is a recapitulation and return to the tonic key with the perfect authentic cadence.
I hope you will find this exercise useful. Melodies in this binary form can easily be created and used as hymn introductions or interludes. If you could do this, you will never be in need in looking for specially created hymn introductions by other composers because you can improvise or compose them yourself.
All you need is a four measure excerpt of your desired hymn and this binary form.
(OPTIONAL) if you want to create a modulating interlude to connect two verses in different keys or two different hymns, then you need to finish your melody in another key.