The Wind in the Willows by Kenneth Grahame is not really a book that addresses a central problem or issue. It is not about social justice or people struggling with trauma, but rather meant to be an expression of love for the English countryside, river life, and rural tranquility, a relaxing and enjoyable tale with extended descriptions of the beauties of the natural world for readers to savor with a nice cup of tea.
The animals in the book, like people, are in search of a relaxed, happy, and safe lifestyle, and Toad, Rat, and Mole develop more mature characters over the course of the story. Toad is rich and irresponsible, and with the help of his loyal friends he overcomes his impulsive nature, to a certain degree, to live a safer, more responsible, and more settled life. Mole gets lost and struggles to find safety and security. Toad's irresponsibility jeopardizes the safety and security of the friends and their quest for a trouble-free and peaceful life, but over the course of the plot, these problems are solved by a combination of mentoring by Badger, maturity, and the fundamental loyalty and decency of the friends.
Perhaps the central problem is how to avoid the greed, impulsiveness, immaturity, ambition, and restless in our own natures that can impede us in our journey towards a happy life and the solution is gratitude and appreciation for friendship and the beauties of nature.