Paul is referring here to an essential principle of Christian doctrine: Commandments that relate to perishable things are basic to the material world, but not basic to the Kingdom of God. In such a sense they are relative to the world but are not absolutely absolute.
1. These commandments concern things which perish with the using; therefore, they cannot be imperishable. Thus, for instance, customs related to washing of hands and feet before sitting for dinner may apply in one culture but they don't apply in another.
2. These commandments are according to the commandments and doctrines of men; they are not based directly on the nature of God. They may relate to the nature of the world (e.g. considering the environment, ecology, and climate of a region), but they don't matter to the environment of the Kingdom of Heaven. Thus, for instance, there are dietery customs on earth, but these are relative only to the ecology of the world. In the absolute sense, dietery customs have no significance (There are no dietery laws in heaven). One must not confuse customs enacted as a matter of convenience with absolutes that cannot be compromised with matters of convenience.
3. These commandments indeed (practically) have an appearance of wisdom in self-imposed religion. When these customs and commandments refer to a religious doctrine, they may have the appearance of wisdom (may look very cogent and logical). But, elevating these to the status of religion (or spiritual discipline) doesn't elevate them essentially; for, essentially they are elements of the universe alone.
4. These may have appearance of false humility. Abstaining from certain foods or things natural to the body are not actually practices of humility. For instance, a person who chooses to use the old type-writer when he can get a modern computer is not practicing humility. Such humility is false. Similarly, one is not proud if he is wearing a costly garment (Note that Jesus had a seamless robe and yet He was the meekest of all). Humility is a spiritual attitude.
5. These commandments may have the appearance of a neglect of body. One must remember that neglect of body is not a Christian virtue at all. The Bible is positive about the human body. The New Testament compares a man loving his wife with him loving his own body (Eph.5:28). Ascetic methods like growing long hair without grooming them, not washing for weeks, and the like are only attempts to neglect the body, but they don't strengthen the spirit in any way.
6, But, all of these have "no value against the indulgence of the flesh." For, as a matter of fact "with the mind I myself serve the law of God, but with the flesh the law of sin." (Rom 7:25 NKJ). In other words, carnal methods cannot fulfill the Law of God.
A person who has known Christ doesn't spiritualize natural elements, because he knows that salvation is not from beneath but from above. His affections are set on things above, not on things below (Col.3:1,2,3).