I have read all of Thoreau’s books, and have also read all the major biographies of him.
The stories of Thoreau having a special relationship with animals is pure mythology. It isn’t true. He never wrote about it. No one who knew him ever said he had any special relationship with animals.
Thoreau was quite antagonistic towards Christianity. He was very enthusiastic about Hinduism.
Thoreau did have a strong sense of justice, however. He was strongly against slavery at a time when being strongly anti-slavery wasn’t “cool” even in his state of Massachusetts. He also strongly opposed the U.S. invasion and forced annexation of the northern Mexican states, a position he shared with Congressman Abraham Lincoln, President John Quincy Adam, and Lieutenant Ulysses S. Grant.
I would not recommend any interest in Thoreau. He was an odd person. He was a loner. He never married. Most everyone found him strange. Even his supposed best friend, writer Ralph Waldo Emerson, said in a eulogy at Thoreau’s funeral that he though Thoreau had not lived up to his potential, and had not really accomplished anything.
By contrast, studying the life of St. Francis is well worth it!