Yes, the poem is humorous. It draws out funny situations Dad comes across with, while trying to climb a tree, to rescue a cat. Moreover, Dad's over confidence (about being able to climb the tree very easily as if it were a child's play adds humour to the poem) and the scepticism of Mum adds humour that reaches its height when at the end Dad remains stuck in the tree while the Cat jumps down safely on its own.
