In order to achieve that goal he needed to do something both negatively and positively. Negatively, he viewed personal achievement in a special way. Positively, he held Christ in a unique fashion. He displaced the excellency of knowing Christ for human success. The word is in the plural.
Human success is like a big pile of excrement.
This is not extravagant language. Every standard of human success is viewed as so much excrement by Paul. This is a very vivid portrayal of anything that attempts to compete with the knowledge of Christ Excrement is waste from the human body. The nutriments have been taken out and used by the body. All that remains is waste.