The idea that Mozart wasn’t famous during his life is a notion based on myth. Mozart was extraordinarily known and popular while he was alive. His music was popular and held in extremely high regard by both fellow composers and music lovers alike. He also didn’t die poor. It’s another false myth about him.
He was not as famous as other composers but he was considered a good musician. He was, in fact, managed by his father. His composing was considered good but after his untimely death, his compositions were explored and loved for their simplicity and elegance.